SAN FRANCISCO - Brandon Belt hit a game-ending single to left-center with one out in the ninth, Buster Posey tied it with a two-run homer in the eighth, and the San Francisco Giants rallied to beat the Arizona Diamondbacks 5-4 on Monday night for their seventh straight home victory.
Posey's drive to straightaway center was his second homer of the year and in two days.
Belt's first career walkoff hit came against Tony Sipp (1-1), who allowed a leadoff single to Andres Torres. Brandon Crawford sacrificed him to second. Belt was mobbed by teammates afterward.
"I'm pretty lightheaded and my kidneys hurt right now," Belt said. "Somebody got me."
Jose Mijares struck out two in the ninth before yielding Cliff Pennington's double. Closer Sergio Romo (1-1) relieved in a double switch as Belt entered at first base. Romo retired Eric Hinske on a first-pitch grounder.
Belt delivered hours after manager Bruce Bochy and hitting coaches Hensley Meulens urged the struggling first baseman to slow his body movements down. Joaquin Arias started in his place.
Arizona played its third straight one-run game. Cody Ross hit a two-run single against the team he helped win the 2010 World Series and pitcher Wade Miley hit a towering, tiebreaking drive for his first career home run. But the D-backs couldn't hold a 4-2 lead.
Eric Chavez also hit a solo homer for the D-backs.
Box scores from Monday's games / B2
• Who: D-backs at Giants
• When: 12:45 p.m.
• Radio: 1490-AM