The San Francisco Giants will try to sweep their second straight series against the Houston Astros as the two clubs close out a three- game series on Thursday.

After losing the season series 4-3 in 2011, the Giants have won seven of their eight meetings this year with the Astros. That includes a sweep of a three- game set at home from July 13-15.

The timing of the trip to Houston has been good for San Francisco, which has won nine of its last 12 overall and leads the Los Angeles Dodgers by 3 1/2 games for first place in the NL West.

The Giants maintained that edge with Wednesday's 6-4 win, getting a three-run homer from Hunter Pence in the first inning and a two-run triple by Joaquin Arias in the sixth inning.

Starter Barry Zito struggled through 2 1/3 innings, allowing three runs and seven hits. George Kontos was the first of six pitchers manager Bruce Bochy used in relief and he got the win with 2 2/3 perfect innings.

"First guy in saves you and that's what Kontos did. Gave us two good innings," said Bochy.

Astros starter Dallas Keuchel retired 14 batters in a row after giving up Pence's homer but took the loss. Four of the five runs he allowed over his five-inning start came in the first.

The Astros have lost four in a row and are 1-11 in their last 12 games.

There was also a record-low attendance for the second day in a row at Minute Maid Park. The 13,207 fans Wednesday night came after the teams drew 13,516 on Tuesday.

"The vibe in the clubhouse and in the dugout has been positive," Astros first baseman Brett Wallace said despite the struggles. "I feel like the energy level has been high. We've been in a lot of games we've played."

Ryan Vogelsong seek to keep the Astros out of this game as he goes for a second straight winning start for the Giants.

The 35-year-old righty snapped a two-start slide on Friday, beating the Atlanta Braves despite giving up three homers over 6 1/3 innings. Luckily for Vogelsong, all three homers were solo shots and he allowed only one other hit in the game, moving to 11-7 with a 2.90 earned run average in 24 games this season.

Vogelsong is 2-2 lifetime with a 2.72 ERA against the Astros, who counter with 21-year-old Jordan Lyles.

Lyles beat the Giants in his only previous encounter with them on Aug. 20 of last year. He gave up two unearned runs in five frames.

The righty snapped a six-decision slide and won for the first time since June 26 with a 3-1 decision over the New York Mets on Friday. Lyles allowed a single run on three hits and two walks in six frames as he upped his season record to 3-10 with a 5.47 ERA in 19 starts.