Starlin Castro hit a three-run homer and Edwin Jackson finally got the better of Charlie Morton, leading the Chicago Cubs to a 6-3 victory over the Pittsburgh Pirates on Friday.

Chris Coghlan added a solo shot as the Cubs opened a 10-game homestand with their fourth win in five games. Last-place Chicago also improved to 18-13 since May 17 for the best record in the NL in that stretch.

Jackson (5-7) was removed after five innings, but it was enough to get his first win in four matchups this year against Morton (4-8). The right-handers have faced off more than any other pair of starting pitchers this season in the majors.

Jackson allowed three runs on Jordy Mercer's fifth homer and five hits. He struck out eight and walked two in just his second win in his last six starts.

Pittsburgh rookie Gregory Polanco opened the game with a single to center, extending his hitting streak to 10 games. He is the first NL player to begin his career with such a streak since Juan Pierre's 16-game run for Colorado in 2000.

The Pirates have lost four of five since a four-game winning streak.

Morton retired six in a row before Jackson's one-out single in the third started a string of five consecutive batters reaching safely.

Anthony Rizzo lined a two-run double into the right-field corner before Castro drove an 0-2 pitch over the wall in left for his 11th homer, moving past his total from all of last year.

Morton jerked his head down in disgust when Castro connected, and then turned around to see where the ball was going. Castro's 10th career homer against the Pirates gave the Cubs a 5-0 lead.

Morton also surrendered Coghlan's second homer in the fifth. The six runs in six innings were a season high for Morton, who had won each of his last three starts and was 4-1 with a 2.40 ERA in his previous five outings.

Mercer went deep after Jackson walked the first two batters in the fifth, but that was it for the Pirates. Four Cubs relievers combined for three innings of two-hit ball before Hector Rondon worked the ninth for his eighth save in 10 chances.

Pittsburgh wasted prime scoring chances in the sixth and seventh. The Pirates had runners on first and second with one out in each inning, and came away with nothing each time.

Pedro Alvarez flied out to the warning track in center for the final out of the sixth, taking a frustrated hop between first and second as Ryan Sweeney ran down the long fly ball. Andrew McCutchen struck out to end the seventh.

Jason Grilli pitched the ninth for the Pirates in his first outing since manager Clint Hurdle removed the right-hander from the closer role. Grilli has blown four save opportunities this season after converting 33 of 35 chances a year ago.