PHOENIX — The San Francisco Giants are a playoff contender and the Arizona Diamondbacks are not.

But you couldn’t discern the difference with a program and a spyglass at Chase Field on Monday night. Even the run that separated the teams in the Giants’ 5-4 victory scored in sloppy and dispiriting fashion.
Fred Lewis hit a potential double-play grounder with the bases loaded and one out in the eighth inning, but the ball stuck just long enough in second baseman Augie Ojeda’s glove and Lewis beat the relay throw by a step.
Travis Ishikawa crossed the plate to decide a game that was almost won by default.
Regardless of how it looked or felt, the Giants managed to creep within four games of the idle Colorado Rockies in the wild- card standings. They prevailed mostly because their bullpen turned in another spotless outing after Barry Zito hit the bench in the fifth inning.
Bob Howry, Dan Runzler, Sergio Romo and Jeremy Affeldt delivered the ball to Brian Wilson, who struck out three to record his 35th save.
Wilson allowed a two-out single to Stephen Drew but threw a called 98 mph fastball at the knees — the ninth pitch of the at-bat — to retire dangerous young slugger Justin Upton.
Wilson has a 1.21 ERA in 26 games since the All-Star break and has the look of a dominant force in a playoff series.
Otherwise, there was little to suggest the Giants deserve to play past the first weekend in October. They were 1-for-11 with runners in scoring position and watched second baseman Freddy Sanchez limp off the field, supported by two trainers, after twisting his knee in the first inning.
Both teams lost their second basemen in very bizarre ways. Diamondbacks second baseman Ryan Roberts hurt his ankle in the eighth when he crashed into pitcher Esmerling Vasquez while chasing Aaron Rowand’s bunt.
Rowand, who doesn’t have a sacrifice hit in two seasons as a Giant, put down a beauty after Ishikawa’s third walk of the game. Vasquez’s desperation throw to first base ended up in foul territory — the Diamondbacks’ third error of the game — and put runners on second and third to set up the winning run.
Neither Zito nor Billy Buckner were sharp and both starting pitchers were forced to work harder because of defensive mistakes behind them.
The Giants scored a run in the first inning after Roberts booted Pablo Sandoval’s potential double-play grounder. But with one out and two runners in scoring position, Bengie Molina struck out and Juan Uribe flied out to left field.
It was the fourth consecutive game the Giants scored once in the first inning.
Zito gave it back in a hurry. Chris Young drew a leadoff walk and Mark Reynolds squared up on the first pitch he saw for his 43rd home run of the season.
Moments later, athletic trainer Mark Gruesbeck attended to Sanchez on the infield dirt. Replays showed that Sanchez’s knee appeared to catch after he received a throw from center field and turned to check the runner.
Sanchez began to limp off the field with Gruesbeck as a crutch. He stopped a few steps away from the dugout and head athletic trainer Dave Groeschner went out to offer additional support.
Sanchez has played in just 25 of 48 games since the Giants acquired him from Pittsburgh for pitching prospect Tim Alderson. His left knee sidelined him at the time of the trade, but the Giants medical staff gave him a thorough examination before signing off on the deal.
Sanchez also missed time with right knee soreness and went on the disabled list because of a strained muscle in the back of his left shoulder.
The Giants must make a decision on Sanchez’s $8.1 million option or choose a $600,000 buyout. The two sides were expected to exchange thoughts on a multiyear contract after the season.
A significant injury could change those plans, though.
Kevin Frandsen replaced Sanchez and the Giants rallied to take the lead. Ishikawa walked and scored on Randy Winn’s ground out to tie the score in the fourth inning.
The Giants pulled ahead in a two-run fifth that Sandoval ignited with his NL-best 43rd double. Sandoval scored on Molina’s single and Rowand hit a deep sacrifice fly with the bases loaded.
But Zito couldn’t hold the Diamondbacks and shortstop Uribe gave them one life too many. Uribe dropped a throw at second base to load the bases for Upton, who lined a tying, two-run single.
Howry entered and Reynolds hit a scalding line drive that almost took Uribe’s glove off. Roberts flied out to strand two runners.