Arizona manager Kirk Gibson had his lineup tuned to face Barry Zito and it produced some early results.

Then Zito went down with a sprained right foot in the second inning, and the Diamondbacks' offense left with him in a 5-3 loss to the San Francisco Giants on Saturday night.

"The way I had my lineup set up with all the righties in there and Zito goes out after one and two-thirds," Gibson said. "Their bullpen responded as good as you can ask giving up one run. When it rains it pours. Right now we have to fight through it. "

Arizona lost its third straight to fall to 3-5 on a nine-game home stand that ends with the series finale against San Francisco on Sunday.

When Zito left, Guillermo Mota came on for 4 1-3 innings of solid relief, his longest stint in 672 major league appearances over 13 major league seasons as the Giants won their fourth straight and seventh in nine games after a 1-4 start.

"He came in and did a good job," Arizona's Xavier Nady said. "He limited us to very few runners and we never really got anything going after Zito came out."

Zito was on crutches, the middle of his right foot swollen noticeably, as he contemplated the possibility that he might miss a start due to injury, something that's never happened to him in his major league career. He already had come back from a serious car accident on the eve of opening day to make his regularly scheduled first start.

"Yeah," he said when asked if the streak crossed his mind. "When I feel my foot and it's pretty painful. I couldn't throw my pitch too well, but there are incredible things that can happen. I was able to recover from that accident and that was huge so we"ll see. We'll see what the MRI says tomorrow and just go out and take it day by day."

Freddy Sanchez doubled in the tying run in the sixth inning, then put San Francisco up for good with a two-run single in the seventh.

Mota (1-0) allowed one run on three hits, fanning four with no walks.

Brian Wilson pitched a perfect ninth and has a save in each of the last four games for the Giants.

The Diamondbacks tied a franchise record by converting five double plays to erase a big share of San Francisco's 13 hits.

Buster Posey hit a two-run homer in the first inning off Joe Saunders (0-3), who gave up five runs on 12 hits in 6 2-3 innings.

"The first home run to Posey he mislocated," Gibson said of his left-hander's performance. "Other than that he battled his tail off."

Saunders got a line drive to the foot but stayed in the game for a while.

"He got drilled didn't want to come out," Gibson said. "We were thinking of letting him go on but he walked two of the last three hitters and I knew his foot was hurting him so I brought in Sam (Demel) who I thought would get us out of the inning. "

Demel relieved the Arizona starter and Sanchez's soft single between third and shortstop brought in two runs to put the Giants back ahead, 5-3.

Arizona scored two off Zito in the second on doubles by Chris Young and Miguel Montero, sandwiched around a four-pitch walk to Xavier Nady. That brought up Saunders, who bunted toward the mound. Zito appeared to catch his right cleat in the turf as he lunged to make the catch.

After he was unable to continue, Mota came on to get Willie Bloomquist to bounce out to short to end the inning.

Arizona took a 3-2 lead on Melvin Mora's RBI double, with the 39-year-old Diamondback tagged out by several feet trying for third on the play.

Posey's second home run of the season came with two outs on a 1-2 pitch, the ball making it to the seats in left-center, to the left of a 413-foot sign.

NOTES: Bloomquist went 0 for 4, ending a 10-game hitting streak that was tied for a franchise-best to start a season. ... Montero has reached base in all 12 games, 10 of them on hits. ... The Giants have homered in the first inning in both games to start the Arizona series. Pablo Sandoval had a three-run shot in the 5-2 victory on Friday night. ... San Francisco manager Bruce Bochy turned 56 on Saturday. ... The five Diamondbacks double plays came in the first six innings.