JACKSONVILLE, Fla. — What was arguably the toughest division in the league last season has crumbled faster than Peyton Manning can sign an endorsement deal.

Indianapolis no longer has a stranglehold on the AFC South, Jacksonville is on the verge of a meltdown and Houston is once again bringing up the rear.

Tennessee, meanwhile, is pulling away.

The undefeated Titans have a four-game lead at the midway point of the season, a big enough cushion that Colts coach Tony Dungy has even conceded the division title. Tennessee avoided the slow start that plagued its three division rivals and might very well be the only AFC South team playing in the postseason.

The Colts have won five consecutive division titles, starting the last three seasons with at least seven straight wins and forcing the Titans, Jaguars and Texans to play catch-up way more often than any of them would like. But injuries may have cost the champ a shot at another title.

Manning has clearly not been himself after missing training camp following two procedures on his knee, and injuries to running back Joseph Addai and safety Bob Sanders have the Colts off to their worst start since 2002.

The Titans have taken advantage — and a seemingly insurmountable lead.<

Tennessee Titans (8-0)

The Titans looked like they might have a huge distraction on their hands after the season opener. Vince Young went missing after he sprained his left knee against Jacksonville, and coach Jeff Fisher called police for help finding his franchise quarterback.

SWAT officers and crisis negotiators showed up to lend a hand, and it was believed Young might have tried to commit suicide. Young denied that, saying the whole incident was blown out of proportion.

The rest of the team rallied around backup Kerry Collins, and the Titans have won every game with the 14-year veteran under center.

Collins' numbers aren't great — he's completed 57 percent of his passes for 1,236 yards, with three touchdowns and three interceptions — but thanks to the AFC's top rushing offense and the league's stingiest defense, he doesn't have to do much.

"We've got eight down and eight more to go," linebacker Keith Bulluck said. "We're at the halfway point, we haven't lost and that's great. But there's another half of football to play. We're sitting nice right now, but our attitude and our mentality definitely won't change."

Grade: A.

Indianapolis Colts (4-4)

Manning's knee has been more analyzed, scrutinized and criticized than Dungy's future or the team's shaky run defense. The two-time league MVP, a model of consistency over his first decade in the league, got off to the worst start since his rookie season.

With 12 touchdown passes and nine interceptions, he's on pace for the fewest TDs in his career and the most INTs since 2002. He also has his lowest quarterback rating (83.3) since his rookie season.

A year ago, Manning threw 31 touchdowns and 14 interceptions and had a rating of 98. But after two operations on his left knee in July, sitting out the preseason and throwing as many wobbly passes as you see in a parking lot pickup game, many wonder whether he's just not right.

He looked considerably better Sunday night against New England, completing 21 of 29 passes for 254 yards and two touchdowns. The rest of the month will give a better indication, with road games against Pittsburgh, San Diego and Cleveland.

Indy also got Addai and Sanders back in the starting lineup against the Patriots, which could be huge — just probably not enough to win another division title.

Grade: C.

Jacksonville Jaguars (3-5)

Things are starting to unravel for a franchise that opened the season with Super Bowl hopes. After placing their top three guards on injured reserve, starting 0-2 and getting little contribution from high-priced free agents Jerry Porter and Drayton Florence and first-round draft pick Derrick Harvey, the Jaguars are now facing chemistry problems.

Or maybe something worse.

Coach Jack Del Rio sent linebacker Mike Peterson home Wednesday, two days after Del Rio openly questioned his team's lack of chemistry.

Del Rio also shuffled some locker assignments, possibly sending a message to his players about who's in charge. He may have done more, too. There wasn't the usual game of dominoes going on in the middle of the locker room, and there weren't any CD players or televisions blaring.

"Sometimes a little change is good," Del Rio said.

The Jaguars can only hope it carries onto the field. Although Jacksonville is the only team in the league to have every game decided by seven points or less, the Jaguars are coming off consecutive losses to Cleveland and Cincinnati and look out of sync on both sides of the ball.

With Detroit up next, the Jaguars are trying to avoid becoming the first team in NFL history to lose consecutive games to winless teams this late in the season.

Grade: D.

Houston Texans (3-5)

The Texans would be the hottest team in the division if not for Tennessee. They've won three of the last four after an 0-4 start that could be partly blamed on Hurricane Ike, which swept through Texas in September and left behind a wake of destruction.

The Texans recovered. But now they're having to change quarterbacks again.

Sage Rosenfels will replace Matt Schaub (knee) for at least the next two games, maybe longer. Rosenfels' first start this season didn't go very well. He fumbled twice, allowing the Colts to erase a 17-point fourth-quarter deficit and win 31-27.

Without that debacle, the Texans would be right in the middle of the crowded AFC playoff race. Instead, they're in the AFC South basement, where they've ended five of their six seasons. The next four games against Baltimore, Indy, Cleveland and Jacksonville likely will determine if they stay there.

Grade: C.