PITTSBURGH -- Gregory Polanco hit a go-ahead, three-run homer in the fifth inning and the Pittsburgh Pirates turned two misplays by the San Diego infield into four runs during a 6-4 win over the Padres on Tuesday night.

Pirates rookie right-hander Chad Kuhl (2-0) overcame a two-run Padres first -- this one aided by a defensive mistake, as well -- while pitching effectively for six innings to get the win. He hadn't started since holding Washington to one run in six innings on July 17.

David Freese singled and scored during each of his first three at-bats, Sean Rodriguez drove in two runs during a spot start at shortstop and Francisco Cervelli finished off Pittsburgh's four-run fifth against Luis Perdomo (5-6) with an RBI double.

Wil Myers hit his 22nd homer of the season leading off the eighth against Pirates reliever Antonio Bastardo, and Jabari Blash led off the ninth with his second, against new Pittsburgh closer Tony Watson. But the Padres managed only five other hits against Kuhl and three relievers.

Polanco batted cleanup for the first time in 339 career major league games and rewarded manager Clint Hurdle by breaking a 2-2 tie with a three-run homer in the fifth against Perdomo.

Josh Harrison started the inning with a single and then was ruled safe at second after apparently being picked off when he managed to slide around the tag. Andrew McCutchen walked ahead of Polanco's 16th homer of the season, into the right-field seats.

The Pirates added a fourth run in the inning on Cervelli's double.

Long before that, the Padres turned a misplay by McCutchen in center -- though it wasn't ruled an error -- into a two-run first inning against Kuhl, who was making his fifth career start.

After Yangervis Solarte drew a two-out walk, Alex Dickerson lined a shot to center that McCutchen played routinely -- only to have the ball sail over his head and to the wall as Solarte scored. Kuhl issued his second walk of the inning before Jabari Blash lined an RBI single to left field.

A Padres misplay -- this one ruled an error -- allowed the Pirates to get a run back in the second. Freese singled and then was safe at second when shortstop Jose Rondon was judged to be off the bag during what looked to be a routine force-play grounder. Three batters later, Rodriguez's groundout drove in Freese.

Freese singled again leading off the fourth and Rodriguez drove him in, this time with a two-out single to center.

NOTES: The Pirates returned RHP Curtis Partch to Triple-A Indianapolis so rookie RHP Chad Kuhl could start against the Padres. ... The Padres won two of three from the Pirates in April, but none of the three San Diego starting pitchers in that series -- Colin Rea, Drew Pomeranz and James Shields -- are in the rotation currently. ... Pirates RF Gregory Polanco (shoulder) returned to the lineup after not starting the previous four games. He batted cleanup for the first time in the majors. ... Pirates rookie RHP Tyler Glasnow (shoulder) pitched a three-inning simulated game Tuesday at PNC Park. He is expected to throw a bullpen session in a few days before beginning a rehabilitation assignment. Glasnow made only two starts in the majors before getting hurt.