A look at the eight first-round series in the NBA playoffs, which start this weekend:

EASTERN CONFERENCE

No. 1 CLEVELAND CAVALIERS (61-21) vs. No. 8 CHICAGO BULLS (41-41).

Season series: Tied, 2-2. The Bulls won at Cleveland in November during the Cavaliers' 3-3 start, then pulled out a 109-108 home victory on April 8 when LeBron James was resting. The Cavs limited the Bulls to an average of 86 points in winning the other two meetings, though Chicago was without Derrick Rose, Joakim Noah and Luol Deng in one of them.

Storyline: The loaded Cavaliers begin the chase for a first NBA championship, hoping not to have any early rust after sitting James for the final four games of the regular season and choosing not to bring Shaquille O'Neal back from his February thumb injury. Chicago won its final three games to grab the last spot and was a dangerous underdog last year, pushing Boston to seven games in a thrilling first-round series.

Key Matchup I: Mo Williams vs. Rose. Rose, last season's Rookie of the Year, was at his best down the stretch after finally shaking some frustrating injuries earlier in the season. Williams scored 35 points in the last meeting and made 18-of-34 shots over the last two. However, he was just 9 of 26 in the first two matchups, the kind of ugly shooting that will remind Cavs fans of his struggles late in last year's postseason.

Key Matchup II: Antawn Jamison vs. Taj Gibson. Jamison is supposed to be the final piece of the Cavs' championship puzzle, and he scored 23 points in the final game against the Bulls. Gibson had a pair of double-doubles against the Cavs, including a 20-point, 13-rebound performance, and Chicago needs his toughness against Cleveland's big frontcourt.

X-Factor: Noah. Terrific finishing stretch included 17 points and 15 rebounds in Bulls' home victory over the Cavs. He wasn't nearly as effective in his other two games against Cleveland, and he'll have to overcome a weight disadvantage inside against the likes of O'Neal and Zydrunas Ilgauskas.

Prediction: Cavaliers in 5.

No. 2 ORLANDO MAGIC (59-23) vs. No. 7 CHARLOTTE BOBCATS (44-38).

Season series: Magic, 3-1. Orlando won the first three meetings before the Bobcats snapped the Magic's eight-game winning streak with a 96-89 victory on March 14 in Orlando. Two of the Magic's wins came way back in November, the second on the night Stephen Jackson made his debut with Charlotte on Nov. 16.

Storyline: The Magic's quest to return to the NBA finals starts against a postseason newcomer. Charlotte is making the first playoff appearance in the franchise's six-year history.

Key matchup I: Vince Carter vs. Jackson. Carter rebounded from a brutal stretch in January to play well in the second half, providing some of the explosiveness the Magic lacked last year in their finals loss. The tough and always-confident Jackson has made a huge difference since his arrival in Charlotte and has tons of postseason experience, which the Bobcats severely lack.

Key matchup II: Rashard Lewis vs. Gerald Wallace. Perhaps while adjusting to Carter's arrival, Lewis hasn't played as well as he did last year, but now is when it really matters. He can start by playing better than he did while averaging just 10.3 points and making only 5-of-25 3-pointers in three games against the Bobcats. Like Lewis, Wallace causes matchup problems at the 4-spot and made his first All-Star game. He averaged 11 points and 9.3 boards against Orlando, but probably has to be more effective offensively after making only nine field goals in three games.

X-factor: Tyson Chandler. Another injury-plagued season for the center ended with him leaving the Bobcats' finale with hip and left elbow injuries. Charlotte could use him on the floor to help defend Dwight Howard.

Prediction: Magic in 6.

No. 3 ATLANTA HAWKS (53-29) vs. No. 6 MILWAUKEE BUCKS (46-36).

Season series: Hawks, 2-1. All three games were close, with Atlanta's 104-96 victory on Monday the largest margin of victory in the series. Al Horford had double-doubles in all three games and could put up even bigger numbers without Andrew Bogut to help defend him. John Salmons averaged 30.7 points for Milwaukee. Brandon Jennings shot just 10 of 36 (28 percent).

Storyline: The Hawks reached the second round last year and are hoping they're ready to go even further this time. Their road may have gotten easier when the Bucks, no longer considered as dangerous an underdog since Bogut's season-ending injuries, fell to the No. 6 seed.

Key matchup I: Joe Johnson vs. Salmons. If they can duplicate their duels from the regular season, this will be an entertaining series. Salmons outscored the All-Star guard 32-24 in the first meeting and 32-27 in the second, before Johnson went for 31 to Salmons' 28 in the last game.

Key matchup II: Jamal Crawford vs. Jerry Stackhouse. A couple of veteran guards who can get hot in a hurry from the outside off the bench. Plenty of eyes will be on Crawford to see how the leading candidate for the sixth man award will fare in his first postseason action.

X-factor: Ersan Ilyasova. With Bogut out, Ilyasova could see heavy minutes off the bench, including some at center, where the 6-foot-9 Turkey native would have to match up with the likes of Horford and Josh Smith.

Prediction: Hawks in 6.

No. 4 BOSTON CELTICS (50-32) vs. No. 5 MIAMI HEAT (47-35).

Season series: Celtics, 3-0. Boston has won 11 of the last 12 meetings, winning the three games this season by seven, six and five points. The Celtics' sweep this season came despite missing Kevin Garnett in one game and Paul Pierce in another. Dwyane Wade had a 44-point game in an overtime loss and averaged 33.7, while Rajon Rondo averaged 20 points and 11 assists.

Storyline: The Celtics, despite a poor finish and an underachieving second half of the season, insist they can still be title threats because their Big Three of Garnett, Pierce and Ray Allen is healthy. However, the Heat played far better down the stretch, and Wade gives them a chance at the upset here.

Key matchup I: Allen vs. Wade. One of the NBA's best jump shots wasn't falling as much this season, as Allen's average of 16.3 points was the lowest since his rookie season of 1996-97. But if he's on in the playoffs, it will force Wade to work defending either he or Rondo, and that could affect him on the other end.

Key matchup II: Kendrick Perkins vs. Jermaine O'Neal. O'Neal said a late-season ankle injury wouldn't be a problem. The Heat have to hope he's right because they don't have many good options at center against Perkins, who had a pair of double-doubles against Miami.

X-factor: Nate Robinson. That's what Boston coach Doc Rivers has said, saying the trade for the former Knicks guard who will be making his postseason debut will have been worth it if Robinson comes off the bench and wins a game for the Celtics.

Prediction: Celtics in 7.

WESTERN CONFERENCE

No. 1 LOS ANGELES LAKERS (57-25) vs. No. 8 OKLAHOMA CITY THUNDER (50-32).

Season series: Lakers, 3-1. Los Angeles won the first three meetings before the Thunder's 91-75 home victory on March 26 that snapped their 12-game losing streak in the series. Kobe Bryant averaged 32.3 points in the first three meetings, then was held to 11 on 4-of-11 shooting while committing nine turnovers in the finale. Kevin Durant scored 25.8 per game for Oklahoma City.

Storyline: After stumbling a bit late in the season while dealing with some injuries, the defending champion Lakers try to put everything together for a run toward a third straight NBA finals appearance. The Thunder were one of the league's biggest surprises and earned their first postseason berth since moving from Seattle. Durant led the NBA with 30.1 points per game and Bryant was fourth at 27.0

Key matchup I: Ron Artest vs. Durant. Artest was largely a disappointment during the regular season, but his true value won't really be measured until he has defended some of the high-scoring forwards the Lakers could face. First up is the 21-year-old Durant, the league's youngest scoring champion ever.

Key matchup II: Bryant vs. Thabo Sefolosha. Sefolosha isn't much of a scorer, but is a very good defensive guard. With Bryant struggling with his shot while dealing with a broken index finger on his right hand, the Thunder have hopes of somewhat containing last season's NBA finals MVP.

X-factor: Andrew Bynum. Bynum averaged 19.3 points on 63 percent shooting in the first three meetings. He'll likely be rusty, but if he plays anywhere near the way he did against the Thunder in the regular season, there's nobody on the other side who can defend him.

Prediction: Lakers in 5.

No. 2 DALLAS MAVERICKS (55-27) vs. No. 7 SAN ANTONIO SPURS (50-32).

Season series: Mavericks, 3-1. Little can be determined from this year's series, because the teams have never really seen each other at full strength. The first three meetings came before the Mavericks acquired Caron Butler and Brendan Haywood in February, and the last one came on the final night of the season, when the Spurs rested Tim Duncan and Manu Ginobili. Dallas won that game to set up this series.

Storyline: Second straight playoff meeting and third in five years for the division rivals from Texas. The Mavericks won both of them, taking a thrilling seven-game series in 2006 on their way to the NBA finals, then knocking off an injury-weakened San Antonio team last year.

Key matchup I: Dirk Nowitzki vs. Tim Duncan. Neither team had any success stopping the All-Star forwards during the regular season. Duncan averaged 26.5 points and 13 rebounds in two games, while Nowitzki had a 41-point night among his 28.8 points per game.

Key matchup II: Butler vs. Ginobili. Ginobili, who missed last year's series because of injury, carried the Spurs late in the season by playing sensational basketball after moving into the lineup when Parker was injured. Butler, a natural small forward serving as a big guard since his move to Dallas, could present matchup problems because of his size and strength.

X-factor: Richard Jefferson. He didn't play nearly as well as the Spurs would have hoped after acquiring him last summer, but he had some good nights against the Mavs. He had a 29-point game and was in double figures in two other meetings. San Antonio needs him to play that well here against a more athletic team.

Prediction: Spurs in 7.

No. 3 PHOENIX SUNS (54-28) vs. No. 6 PORTLAND TRAIL BLAZERS (50-32).

Season series: Trail Blazers, 2-1. Portland averaged 106.5 points while winning the first two meetings before the Suns showed their defensive improvement in a 93-87 victory on March 21. None of the games was decided by more than seven points.

Storyline: Strong bounce-back season for the Suns after missing the playoffs last year landed them the No. 3 seed. Phoenix was 23-6 since the All-Star break and gets a Portland team that will be without its best player. Brandon Roy has a torn meniscus in his knee that will require surgery. He is scheduled to have surgery on Friday.

Key matchup I: Amare Stoudemire vs. LaMarcus Aldridge. Stoudemire averaged 23 points and 11.3 rebounds against Portland and may have been the league's dominant power forward down the stretch. Aldridge isn't too far behind, but he'll have to be even better as Portland's No. 1 option since Roy can't go.

Key matchup II: Steve Nash vs. Andre Miller. Nash still might be the NBA's best point guard at playing fast, but Miller likes to push the tempo, too. He averaged 21 points in the last two meetings, while Nash had a pair of double-doubles against Portland.

X-factor: Rudy Fernandez. Portland will need everyone to step up since Roy is unavailable, and the flashy Fernandez would love to be the guy. He proved he can play in big-time games when he scored 22 points against the United States in the 2008 Olympics gold-medal game.

Prediction: Suns in 6.

No. 4 DENVER NUGGETS (53-29) vs. No. 5 UTAH JAZZ (53-29).

Season series: Nuggets, 3-1. Denver earned the tiebreaker and home-court advantage in this series by winning the first three meetings to clinch the season series. The Jazz may come to regret a 105-95 home loss on Jan. 2, a game in which neither Chauncey Billups nor Carmelo Anthony played. Utah won the other game both missed, but the two All-Stars were unstoppable when they did play, with Anthony averaging 33.5 points and Billups 27.

Storyline: In the balanced Western Conference, either of these teams is capable of knocking off the defending champion Los Angeles Lakers in the second round. However, one of them won't even get past their opening series. Denver hopes to get coach George Karl back from his cancer treatments if it advances.

Key Matchup I: Billups vs. Deron Williams. Williams had three 20-point games, but his size and physical play doesn't bother Billups the way it does many other point guards. And Billups, a former NBA finals MVP, is one of the league's most clutch postseason performers.

Key Matchup II: Kenyon Martin vs. Carlos Boozer. If both are healthy — both were on the bench with injuries when their seasons ended — this is a good matchup of rugged power forwards. Boozer had double-doubles in all four games but Martin was nearly as sharp, collecting three double-doubles.

X-Factor: Nene. Had only four points in the final meeting, but before that hurt Utah with some surprising offense. He averaged 18.7 points in the three victories.

Prediction: Nuggets in 7.