Pittsburgh Pirates' Neil Walker (18) is greeted by Jung Ho Kang after driving him in with a two-run home run during the sixth inning of a baseball game against the San Francisco Giants, Thursday, Aug. 20, 2015, in Pittsburgh.

PITTSBURGH — Neil Walker was more impressed by his team's starting pitcher than his home run.

Charlie Morton combined with two relievers on a six-hitter and Walker hit a two-run home run to lead the Pittsburgh Pirates over the San Francisco Giants 4-0 on Thursday night.

Morton (8-4) scattered four hits over 6 2/3 innings while striking out eight and walking two. He was pulled in the seventh inning with a four-run lead after the Giants loaded the bases with two outs.

“It's fun to play behind him when he's going well because he gets a lot of ground balls that lead to a lot of quick innings and you get on and off the field in a hurry,” Walker said. “He was really good tonight.”

Jared Hughes, who got Gregor Blanco to line out to end the seventh-inning threat, and Tony Watson completed the shutout.

Walker hit his 13th home run in the sixth inning off Jake Peavy (3-6) to push the Pirates' lead to 4-0. They had gone ahead 2-0 on RBI doubles by Aramis Ramirez in the first and shortstop Jung Ho Kang in the third.

Walker, Kang and Starling Marte each had two hits.

The Pirates (72-45) moved a season-high 25 games over .500 with their seventh win in eight games, pulling within 4 1/2 games of the idle St. Louis Cardinals in the NL Central.

“We're playing really well right now and it's a situation where everyone is contributing, one through 25 on the roster,” Pirates manager Clint Hurdle said.

The Giants dropped 2 1/2 games behind the Los Angeles Dodgers, who were off, in the NL West.

Peavy allowed four runs and seven hits in six innings with five strikeouts and one walk. He had won all three of his career starts at PNC Park but was pitching in Pittsburgh for the first time since 2008.

“I thought he settled down,” Giants manager Bruce Bochy said. “He was throwing the ball well. We just couldn't generate any offense. Their guy was just really good.”

Pirates 3B Josh Harrison (torn left wrist ligament) and SS Jordy Mercer (sprained left knee) could return from the disabled list sometime during the four-game series that ends Sunday, according to manager Clint Hurdle. ... 1B/OF Corey Hart (left shoulder impingement/right knee discomfort) began a rehab assignment with Triple-A Indianapolis.

The Pirates signed outfielder Travis Snider, who played for them the previous three seasons.