By Jeremy Kahn

Even with Brandon Belt back in the lineup, the San Francisco Giants still are unable to break out of this rut that now sees them in second place in the National League West.

Eric Stults pitched seven strong innings, as he he and two other relievers combined on a four-hit shutout and the San Diego Padres defeated the Giants 2-0 in the opener of their three-game series at Petco Park.

Joaquin Benoit pitched a perfect eighth inning, and then closer Huston Street hit the final three outs for his 23rd save of the season.

It was the first win for Stults in his last nine starts, as he snapped a six-start losing streak and for the first time in two months.

Belt went 0-for-4 including a strikeout in his first game since breaking his wrist earlier this season, as the Giants dropped their third straight game and are now one and one-half games behind the Los Angeles Dodgers in the National a League West.

Once again, it was a tough night for Matt Cain, who lost for the fourth straight time and saw his record for the season fall to 1-7.

Cain allowed two runs on seven hits in six and one-thirds innings, as he is now winless in seven straight starts.

Alexei Amarista hit a solo home run in the bottom of the third inning, and then Chase Headley drove in Seth Smith with a single later in the inning for the only runs allowed by Cain and the Giants pitching staff on the afternoon.