Giants 3, Astros 2 (12): Hector Sanchez hit a walk-off single off Brett Myers as San Francisco handed Houston its 12th straight road loss.

Pablo Sandoval and Angel Pagan opened the bottom of the 12th with singles before Sanchez's single off Myers (0-4) went past second baseman Jose Altuve, allowing Sandoval to score from second. San Francisco reclaimed first place in the NL West with the win.

The Astros forced extra innings by rallying with two runs in the top of the ninth off Santiago Casilla, who blew his fourth save in his last six chances.

After Casilla allowed Justin Maxwell’s RBI double with two outs, Maxwell scored from second when the Giants were unable to throw out Chris Snyder at first after he struck out on a dropped third strike.

The late-inning drama overshadowed an impressive outing by Giants starter Tim Lincecum, who allowed five hits with one walk and a season-high 11 strikeouts over eight scoreless innings.

Melky Cabrera put San Francisco on the board with an RBI single in the fifth off Lucas Harrell, who exited after throwing 104 pitches over five innings.

The Giants extended their lead in the sixth on back-to-back doubles by Pagan and Sanchez off Fernando Abad to open the inning.

Houston lost for the 12th time in its last 13 games and fell to 0-9 in extra-inning games.

GAME NOTEBOOK: Astros SS Jed Lowrie left the game in the fourth inning with a right ankle sprain. … Jeremy Affeldt (1-1) recorded one out for the win. …Houston fell to 9-34 away from Minute Maid Park. …The Giants have won 19 of their last 26 games at AT&T Park. …San Francisco improved to 5-1 in extra-inning games.