PHOENIX -- As news spread that Barry Bonds had knee surgery again, the San Francisco Giants lost another game -- and maybe another regular.
Chris Snyder had a run-scoring double that capped a four-run fourth inning and made a key pickoff throw, leading the Arizona Diamondbacks over the Giants 6-2 Wednesday.
Brandon Webb (4-0) won for the first time since mid-April and Luis Gonzalez had three hits as Arizona won for the ninth time in 12 games.
Pedro Feliz drove in both runs for San Francisco, which lost its second straight following a six-game winning streak.
Earlier Wednesday, Bonds said on his website that he had a third operation on his injured right knee, the latest setback in the slugger's rehabilitation.
Bonds underwent arthroscopic surgery Monday as doctors tried to clean out an infection, first draining fluids from his knee, according to a journal entry from Bonds posted on his Web site.
"It's the third time that he's going to be out longer, so we are accustomed to that now," Giants manager Felipe Alou said.
Second baseman Ray Durham, who missed two games at Pittsburgh because of a groin strain, was replaced by Deivi Cruz in the middle of the fifth after aggravating his injury.
"Every year since he came to this club he's been having some leg problem," Alou said. "He broke a foot for the first injury, and he was out for four weeks, and then he had a hamstring. Either leg, it doesn't matter. So it's not like we're snakebitten. That's been here for a while."
Webb allowed two runs, four hits and a season-high four walks in six innings in his first win in three starts since April 18 at Colorado. He struck out seven.
"He looks like he's made some adjustments from last year," San Francisco's J.T. Snow said. "He's the kind of guy who can move the ball around and throw it to both sides of the plate."
Brett Tomko (2-4), who had won his previous two decisions, gave up four runs and nine hits in six innings. The Giants have scored a total of five runs in his four losses.
San Francisco went ahead in the fourth when Moises Alou walked with one out and Feliz doubled him home. Feliz was out trying to stretch his hit into a triple. Webb then walked Durham, and Snyder, Arizona's catcher, picked off Durham at first after getting a favorable bounce on a changeup in the dirt.
"It was just one of those go-on-the-fly kind of plays," Snyder said. "It was one of those things -- it wasn't planned, just happened -- and it was a fortunate time that it happened."
Tomko retired his first 11 batters, then allowed six straight hits with two outs in the fourth.
Gonzalez reached with a single a hard grounder that bounced off Durham's glove and chest at second, and Shawn Green blooped a single into right field, with Durham trying for a diving catch but unable to hold the ball.
Alex Cintron, Chad Tracy and Quinton McCracken followed with RBI singles, and Snyder's double put Arizona ahead 4-1.
"An infield hit and then a broken-bat, and then the ball just started rolling," catcher Mike Matheny said. "Earlier in the game, no question. Guys weren't even putting balls in play. That's the way he threw the last game he started."
Snow walked with two outs in the sixth and scored on a Feliz's single. San Francisco loaded the bases in the seventh on Michael Tucker's walk and singles by pinch-hitter Lance Niekro and Omar Vizquel, but Javier Lopez struck out Snow to end the inning.
Arizona added a pair of runs in the seventh off Jeff Fassero after Craig Counsell reached on Snow's fielding error at first. Gonzalez had a run-scoring single to left and Clayton scored on Green's RBI grounder as San Francisco failed to turn what would have been an inning-ending double play.
"When we added on, that was certainly a key to the game," Diamondbacks manager Bob Melvin said. "Four runs still isn't a cushion in my book."
Tucker made a backhanded grab at the warning track on Royce Clayton's fourth-inning drive. ... Counsell went 0-for-4, ending his seven-game hitting streak. ... RHP Jeremy Accardo, called up this week from Double-A Norwich, pitched a hitless eighth inning for the Giants.