Pablo Sandoval hit a two-run homer in the 11th inning to lead the visiting San Francisco Giants past the Houston Astros, 6-4, on Sunday.

Brandon Belt added a three-run shot for the Giants, who avoided a sweep of the three-game set and moved to within 1 1/2 games of the Arizona Diamondbacks in the National League West.

Sandoval came up with two outs and one on in the 11th and took an 0-1 pitch from Mark Melancon (6-4) over the wall in left-center for his 15th blast.

Jeremy Affeldt (2-2) got the win and Ramon Ramirez picked up his third save.

The Giants took a quick lead on Belt’s three-run homer in the second but the Astros came back with four runs in the bottom of the frame to chase Dan Runzler and grab the advantage. Rookies Jose Altuve and J.D. Martinez combined to drive in three runs in the rally.

San Francisco tied it up at 4-4 in the fourth when Mike Fontenot hit a sacrifice fly.

The Giants had a chance to take the lead in the eighth but Martinez threw out Nate Schierholtz at the plate from deep left field to end the threat.