PITTSBURGH -- Erik Kratz hit a home run and starter Jeff Locke led a contingent of four Pittsburgh Pirates pitchers in shutting down the high-flying San Francisco Giants 1-0 Monday.

The Pirates, on the opening night of an eight-game homestand, not only busted up a five-game losing streak, but they did it against Giants ace Madison Bumgarner and against a San Francisco team that had won eight games in a row.

Locke (6-5), who had given up a combined 18 runs over his previous two starts, both losses, pitched 6 2/3 scoreless innings, giving up five hits, striking out three and walking none. He was pulled after Jarrett Parker hit a two-out double to the center-field wall in the seventh.

Against San Francisco, Locke had been 0-1 with a 9.42 ERA in three career starts.

Mark Melancon pitched the ninth for his 20th save.

Bumgarner (8-3), who entered the game with a career-best seven-game winning streak, threw a five-hit complete game in the loss.

Through the first 3 1/2 innings, each team got a single in each inning but didn't threaten to bring a runner home.

In the fifth, with two outs, Kratz sent the first pitch from Bumgarner to left. The ball barely cleared the wall, and left fielder Angel Pagan timed it well and leaped -- only to have the ball go off of his glove. Pagan slammed the glove onto the warning track in disgust.

Kratz's first home run since Aug. 18, 2014, gave Pittsburgh a 1-0 lead. He was acquired earlier this month.

The Pirates went 5-1 against the Giants last year, outscoring San Francisco 32-19 with Pittsburgh's pitchers putting up a collective 2.0 0 ERA against the Giants. Since the beginning of the 2013 season, Pittsburgh is 8-3 against San Francisco at PNC Park.

NOTES: San Francisco 3B Matt Duffy's ironman streak ended on Monday, one day after he became the active leader with 188 consecutive games played. Duffy left Sunday's contest against Tampa Bay after aggravating an Achilles' injury. He was not available Monday and was expected to get an MRI. ... Giants CF Denard Span (neck) was not in the starting lineup but could be available Tuesday. ... Pittsburgh had not named a starter for Tuesday's game as of Monday afternoon, but it is expected that RHP Wilfredo Boscan will be recalled from Triple-A Indianapolis to make the start. ... Pittsburgh pitching coach Ray Searage left before the game started because of back spasms and a flare-up of arthritis in his left wrist. ... The Pirates landed in Pittsburgh at 2:40 a.m. Monday after playing a late night game Sunday in Chicago and did not take batting practice. San Francisco played a day game on Sunday at Tampa Bay before traveling to Pittsburgh.