SAN FRANCISCO — Matt Downs was facing his former team and he insisted that carried no extra motivation.

Downs delivered a go-ahead single with one out in the 11th inning and the Houston Astros beat the San Francisco Giants 4-3 on Sunday to salvage a four-game split.

“Having Downs get the winning hit against his former team was great,” Astros’ starter Bud Norris said. “I know he’s on cloud nine.”

It was also a special homecoming for Norris, a Marin County native who was pitching in the Bay Area for the first time.

“He was back home and he was absolutely outstanding,” Houston manager Brad Mills said. “He didn’t want to come out and I didn’t want him to come out, he was throwing that good.”

Jose Altuve got things going with a one-out double against Ramon Ramirez (2-3) and Downs followed with a single up the middle. Altuve was forced into action after slugger Carlos Lee left in the top of the ninth with a sprained right ankle, sustained sliding into second on a double.

Mark Melancon (7-4) pitched the 10th and got the win despite allowing Mark DeRosa’s tying single.

Houston went ahead 3-2 in the 10th on pinch-hitter Jason Michaels’ double, then the Giants came back again.

Jordan Schafer lined a tying single to right with two outs in the eighth against Matt Cain to help force extra innings.

Aubrey Huff hit a tying RBI single off Houston starter Bud Norris in the seventh to end a 0-for-15 funk, and singled again in the ninth but the Giants didn’t score. After Huff’s initial hit in the seventh, Norris received a mound visit before giving up Orlando Cabrera’s go-ahead sacrifice fly on the next pitch.

Lee doubled against Sergio Romo in the ninth and hustled to beat the throw from right field. He came in hard to collide with shortstop Cabrera. Lee’s right leg bent and it appeared the spikes on his right shoe got caught on the bag. He grabbed his right ankle in pain as the training staff rushed out to help him off the field.

Norris had only allowed one runner to reach second base before the Giants got to him for two runs in the seventh.