PITTSBURGH — Gregory Polanco’s maturation from prospect to entrenched major league starter remains a work in progress. The pace of the Pittsburgh Pirates outfielder’s education, however, is picking up speed.

Facing Cubs reliever Phil Coke with the go-ahead run on second Thursday, Polanco quickly fell behind two strikes. The 6-foot-4 right fielder worked the count full then slapped a single to left field to drive in Josh Harrison with the go-ahead run in a 5-4 win.

Coke intentionally walked pinch-hitter Corey Hart to set up a lefty-on-lefty matchup with Polanco. Though Polanco didn’t take the slight personally, it certainly provided ample motivation.

“You’re more focused and you say, `I want to win this fight,”’ Polanco said. “You always want to be ready every pitch because they walked the hitter before to try and make you out.”

The hit was set up by Josh Harrison’s second double of the game with one out. Chicago rookie Kris Bryant, a third baseman making a spot start in center while Dexter Fowler rested a groin injury, took a roundabout path to the ball, though Cubs manager Joe Maddon hardly placed the blame on Bryant.

“It took a left turn on him,” Maddon said. “It was like a drawn 2-iron. It just hooked left. He had no chance at that.”

Polanco finished 3 for 4 with two RBI. Sean Rodriguez hit his first homer with the Pirates as Pittsburgh rallied from a three-run deficit to manage a split of the four-game series.

“It was arguably for me today one of the best team wins since I’ve been here with what we had, what we went out there with, how we were able to battle,” Pirates manager Clint Hurdle said.

Radhames Liz (1-1) picked up his first major league win since 2008 with two innings of shutout relief. Mark Melancon worked a perfect ninth for his third save.

Chris Denorfia and Starlin Castro each had two hits for the Cubs. Rookie second baseman Addison Russell doubled in a run for the first RBI of his career.

“We probably took the first two games away from them,” Maddon said. “They took the last two away from us, that’s how this division is going to play this year.

Brian Schlitter (0-2) gave up the double to Harrison with one out in the seventh. Polanco’s single put the Pirates in front for the first time and the bullpen did the rest. Liz allowed just one hit in two innings to win for the first time since Sept. 14, 2008, when he played for Baltimore.

Melancon, who struggled while blowing a save on Tuesday, had little trouble setting down Welington Castillo, Russell and Chris Coghlan as the Pirates ended an early 10-game homestand with a 6-4 mark.