Brayan Villarreal walked Marco Scutaro with the bases loaded and two outs in the bottom of the ninth, handing the San Francisco Giants a 3-2 victory over the Boston Red Sox on Tuesday night.
Roger Kieschnick started the winning rally with a one-out single off Franklin Morales (2-1). The Giants loaded the bases with two outs when Morales walked Andres Torres and hit pinch-hitter Hector Sanchez with a pitch on the left wrist.
Villarreal, acquired last month from Detroit, then threw four straight balls to Scutaro in his first appearance with the Red Sox, giving the defending World Series champions a rare reason to celebrate this summer.
The Red Sox couldn't hold a 2-0 lead and lost for the fifth time in seven games to fall percentage points behind Tampa Bay for the lead in the AL East.
Sergio Romo (4-6) pitched a perfect ninth for the win.
After twice failing to get a runner in from third with no outs, the Giants finally delivered in the eighth inning to tie the game.
Scutaro reached on a one-out single and went to third on Brandon Belt's single against Junichi Tazawa. Buster Posey then hit a high fly down the right-field line that Shane Victorino caught in foul territory. Scutaro scored easily on the sacrifice fly but Tazawa escaped without any further damage to keep the score tied at 2.
Victorino helped give Boston the lead when he hit a rare right-handed homer off a righty pitcher. The switch-hitting Victorino is unable to bat left-handed because of an injured left leg. But that did not bother him when he led off the third inning with a drive to left off Ryan Vogelsong that made it 2-0.
It was just the second time Victorino had hit a right-handed homer against a righty in his career, also doing it against knuckleballer R.A. Dickey on Sept. 24, 2010, according to STATS LLC.
It looked as if that 2-0 lead would stand up when Jake Peavy escaped jams in the fourth and fifth innings. Belt, who had three hits, was stranded after a leadoff triple in the fourth when Posey grounded out and Peavy struck out Hunter Pence and Brandon Crawford.
The Giants scored their first run of the series when Kieschnick led off the fifth with a single and scored on Joaquin Arias' triple. But San Francisco couldn't get the equalizer when Vogelsong, Gregor Blanco and Scutaro followed with groundouts.
Peavy got helped out by his defense when second baseman Dustin Pedroia made a diving stop of Vogelsong's hard grounder and rookie Xander Bogaerts threw out Scutaro on a high chopper to shortstop to end the inning.
The Giants went 0 for 10 with runners in scoring position and are 4 for 35 in those situations the past four games. But they scored their last two runs without a hit and won the game.
NOTES: Bogaerts (20 years, 323 days) is a prized prospect who is the youngest position player to appear in a game for Boston since Dwight Evans (20, 318) in 1972. He went 0 for 3 and stranded five runners. ... San Francisco 3B Pablo Sandoval was a late scratch because of a sore back. ... Boston RHP Clay Buchholz (neck and shoulder) threw 46 pitches in a simulated game and is set to make a rehab start Sunday. Manager John Farrell said he would like Buchholz to get three rehab starts but he might only get two depending on the minor league schedule. ... LHP Barry Zito (4-8) makes his first start of the month for the Giants in the series finale Wednesday after Chad Gaudin was placed on the DL. Felix Doubront (8-6) goes for Boston.