SAN FRANCISCO

Brayan Villarreal was put in quite a difficult predicament in his first appearance with Boston.

Unfortunately for the Red Sox, he failed to deliver.

Villarreal walked Marco Scutaro on four pitches with two outs and the bases loaded in the bottom of the ninth inning, sending the Red Sox to a 3-2 loss to the San Francisco Giants on Tuesday night.

Villarreal was wild as soon as he came in to face Scutaro and the game ended when umpire Mike Everitt ruled a close pitch was just out of the strike zone to the dismay of the Red Sox.

“We shouldn’t be in that situation,” catcher David Ross said. “We had a guy that we know who is notorious for taking pitches, we have to throw strike one.”

The Giants squandered numerous opportunities early in the game, going 0 for 10 with runners in scoring position, but they tied it in the eighth inning on a sacrifice fly in foul territory and used two walks and a hit batsman to win it.

Roger Kieschnick started the winning rally with a one-out single against Franklin Morales (2-1) for his third hit of the game. The Giants loaded the bases with two outs when Morales walked Andres Torres and hit pinch-hitter Hector Sanchez on the left wrist.

“We started out the inning in pretty good shape and then seemingly in a matter of about seven or eight pitches it looked like Franklin lost the strike zone a little bit and leaves us in a tough spot with two outs,” Red Sox manager John Farrell said.

With Brandon Workman having pitched the past two days, Farrell gave Villarreal his first appearance with the Red Sox. Villarreal was acquired in a deal last month from Detroit and called up from Triple-A Pawtucket on Monday.

He made a poor first impression, throwing four straight balls to Scutaro.

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.

Scutaro reached on a oneout 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 switchhitting 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 that made it 2-0.

It was just the second time Victorino had hit a righthanded 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.

NOTES: SS Xander Bogaerts (20 years, 323 days) became 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. … Boston RHP Clay Buchholz (neck and shoulder) threw 46 pitches in a simulated game and is set to make a rehab start Sunday. 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 this afternoonn. Felix Doubront (8- 6) goes for Boston.

• Who: Boston Red Sox at
San Francisco Giants.
• Where: AT&T Park.
• When: 3:45 p.m. today.
• Starting pitchers: Boston
(Felix Doubront 8-6) vs. San
Francisco (Chad Gaudin 5-
2).
• TV: NESN.