Updated

Clint Barmes hit a three-run home run in the seventh inning to help the Pittsburgh Pirates to a 3-1 win over the San Francisco Giants in the second of a four-game set.

Barmes' home run made a winner out of Charlie Morton (5-3), who gave up one run on seven hits with a walk and three strikeouts over 7 2/3 innings for the Pirates, who have won four of their last five.

The win allowed Pittsburgh to stay a game ahead of St. Louis for first place in the NL Central as the Cardinals defeated the Atlanta Braves earlier on Friday.

"We're a team that shows up everyday and expects to win," said Barmes. "You don't know who is going to be that guy on a given night. It makes it fun, it makes it exciting."

San Francisco, meanwhile, has lost five of its last six games and sits dead last in the NL West.

Roger Kieschnick drove in the lone run of the game for the Giants, who saw starter Madison Bumgarner (11-8) drop his second straight decision after giving up three runs on seven hits in eight innings of work.

"They got a big clutch hit there and that was the game," said San Francisco manager Bruce Bochy. "Bumgarner pitched a great game and that's the way it goes sometimes."

The first run of this game came across in the fourth inning as Buster Posey doubled with one out and moved to third on a wild pitch from Morton. Kieschnick brought him home with a single to left for a 1-0 lead.

Pittsburgh had stranded a man on base in four of the first six innings, but took the lead in the seventh.

Gaby Sanchez singled to start the inning and Josh Harrison followed with a base hit. After Neil Walker moved the runners over a bag with a sacrifice bunt, Barmes golfed a low pitch just over the left field wall for his fourth home run of the season and a 3-1 lead.

After getting an inning-ending double play in the seventh, Morton got the first two batters out in the eighth before giving up a double to Brandon Crawford.

Tony Watson took over and got Brandon Belt to look at strike three to end the frame.

Mark Melancon came out to close the game in the ninth and gave up an infield single to Hunter Pence with one out, but then got Pablo Sandoval to groundout and struck out Kieschnick for his ninth save of the season.

Game Notes

Pittsburgh has taken four of five from San Francisco this season ... Both teams left six men on base ... Bumgarner is 1-2 over three outings against the Pirates ... Morton improved to 2-5 in nine starts against the Giants ... The Giants placed pitcher Matt Cain on the 15-day disabled list on Friday and purchased the contract of pitcher Yusmeiro Petit from Triple-A Fresno. Also, the team optioned infielder Nick Noonan to Fresno and recalled pitcher Mike Kickham from Fresno.