SAN FRANCISCO -- Sidelined for four days with the flu, Mark Reynolds didn't expect much when he decided he was well enough to play Thursday.
He was wrong.
Reynolds hit his 39th home run of the season as part of a four-run fifth inning for the Diamondbacks, and Arizona ended a disappointing road trip with an 11-0 victory against the San Francisco Giants.
"When I woke up this morning, I stood up in bed and I wasn't dizzy, so I was like 'All right, I'm playing,' " said Reynolds, who also had an RBI single. "I figured my timing would be off and I would feel uncomfortable at the plate, but it was the opposite."
The Giants' seventh shutout loss of the season cost them a chance to gain ground in the National League wild-card race. Colorado, which holds a three-game lead on San Francisco, lost to the Dodgers and comes to AT&T for a pivotal three-game series beginning Friday.
Reynolds missed Arizona's three previous games with the flu and received an IV treatment in San Francisco on Tuesday. The veteran slugger didn't play in the first two games of the series against the Giants but returned Thursday to lead the Diamondbacks to their third-highest run total since the All-Star break.
He had an RBI single during Arizona's three-run first inning then hit a towering home run to center off San Francisco starter Joe Martinez (3-2) with one out in the fifth. The home run was Reynolds' 39th of the season, one behind St. Louis' Albert Pujols, who leads the majors.
Reynolds also made a nice play on Juan Uribe's high popup in the second, falling to his knees just before making the catch.
"Maybe I should play like this all the time, kind of relaxed," Reynolds said. "I still have pneumonia but I felt good enough to play. I can stand up without throwing up so that's a good sign."
Petit (3-8) scattered four hits over six innings and had five strikeouts with two walks to win for the first time since Aug. 4 while the Diamondbacks backed him with their highest run total in three weeks.
"The ending is important for us because we really took it on the chin a lot this road trip," manager A.J. Hinch said. "To win today in convincing fashion after two really gut-wrenching losses and the way we lost is rewarding. Today is certainly a morale lifter."
San Francisco took the first two games of the series behind a three-run home run from Travis Ishikawa on Tuesday and a pinch-hit three-run homer by Bengie Molina on Wednesday. But the Giants couldn't complete the series sweep because they couldn't muster much offense.
Petit, who had lost his previous three starts, retired nine of the first 10 batters he faced and didn't allow a hit until Edgar Renteria's single to center leading off the fourth. The Giants loaded the bases later in the inning with two outs but Petit escaped the jam by getting Aaron Rowand to strike out looking on three pitches.
"We're banged up," manager Bruce Bochy said. "It's the heart of your order so that makes it a little more difficult but you try to see some young guys up there getting a chance and hopefully they step up. But it makes it a little more difficult when you're missing your 2-3-4 hitters."
- Arizona C Chris Snyder did not take batting practice because of lower back pains and will undergo an MRI test in Phoenix, according to Hinch. Snyder was available in an emergency against the Giants and Hinch said a decision likely will be made Saturday whether to put Snyder on the DL.
- San Francisco pitchers recorded 11 strikeouts, giving them 1,008 for the season. It's the seventh time in the past 10 years and the 13th time overall in the franchise's San Francisco history the pitching staff has reached the 1,000 plateau.