Pedro Alvarez scorched a three-run homer to help Jeff Locke run his win streak to eight games, as the Pittsburgh Pirates downed the Philadelphia Phillies, 6-5, Wednesday in the middle test of a three-game set at PNC Park.
Locke (8-1) yielded three runs -- two earned -- on seven hits and three walks over 5 2/3 frames, becoming the first Pittsburgh left-hander to win eight straight decisions since John Candelaria in 1983.
Locke has been charged with three earned runs or less in each of his last 14 starts and hasn't lost since his season debut on April 7 at Los Angeles, a span of 16 starts.
"Everything kind of came together like it usually does when the game progresses," Locke said. "We used the defense again to make great plays. They bailed me out."
Alvarez's 21st homer of the season broke a 1-1 tie in the fifth, while Russell Martin added two hits, two RBI and a run scored for the Pirates, who had won nine straight games before dropping Tuesday's series-opener by a 3-1 count.
Domonic Brown clubbed a two-run homer, while Delmon Young went 3-for-5 with a run scored and collected his 1,000th career hit in the setback, Philadelphia's third in its last four games.
Phils southpaw John Lannan (1-3) was tagged for four runs on 11 hits and three walks over five frames to absorb the loss.
"He wasn't as sharp tonight as he was in Los Angeles," Phillies manager Charlie Manuel said.
The Pirates stranded eight baserunners over the first four frames and trailed 1-0 heading into the fifth before putting up four runs in the home half to seize control.
Andrew McCutchen started the rally with a one-out infield single before Gaby Sanchez followed with a base hit to left.
After Martin ripped a single up the middle to score McCutchen, Alvarez launched a 1-0 fastball into the seats in right-center to provide Pittsburgh with a 4-1 lead.
The Phillies battled back in the sixth, as Young smacked a leadoff single and moved to second on Carlos Ruiz's two-out base hit that chased Locke from the contest.
Justin Wilson was called upon to face pinch-hitter Kevin Frandsen, who punched a single through the right side of the infield to score Young and bring the Phillies within 4-2.
Michael Young followed with a sharp grounder to shortstop that Jordy Mercer couldn't handle, allowing Ruiz to race home to make it 4-3.
The Pirates got both runs back in the bottom half when McCutchen laced a one- out triple off Phillippe Aumont, who then plunked Sanchez before serving up a double to Martin that scored McCutchen for a 5-3 lead.
Jake Diekman then entered from the bullpen and uncorked a wild pitch, allowing Sanchez to score for a 6-3 cushion.
Pittsburgh's Jeanmar Gomez and Mark Melancon each fired a scoreless inning in relief to keep the margin at three before Jason Grilli ran into trouble in the ninth.
Grilli retired the first two hitters in order, but allowed a double to Jimmy Rollins before serving up Brown's two-run blast to right to bring the Phillies within 6-5.
However, the hard-throwing right-hander bounced back by fanning Delmon Young on four pitches to nail down his 28th save of the season.
Early on, the Phillies drew first blood in the fourth, as Brown and Delmon Young stroked consecutive one-out singles. After John Mayberry fanned, Ben Revere looped a single into shallow left field for a 1-0 lead.
Locke is the first Pittsburgh pitcher to make 16 consecutive starts in one season without suffering a loss, surpassing Dock Ellis' mark of 15 straight set in 1971 ... Alvarez is one of only two Pirates third basemen with at least 20 home runs in multiple seasons, joining Bobby Bonilla, who accomplished the feat in 1988 and 1989 ... Delmon Young is the 86th active player with 1,000- or-more hits for his career ... The Phillies fell to 15-25 against the Pirates in Pittsburgh since PNC Park opened in 2001.