CHICAGO -- Matt Szczur made the most of his second chance on Friday.

The Chicago Cubs left fielder delivered a game-winning hit with bases loaded in the bottom of the 12th inning, scoring Starlin Castro from third in an 11-10 walk-off victory over the Pittsburgh Pirates.

Szczur sent a routine fly to shallow right field that dropped for a hit after Pirates right fielder Gregory Polanco tripped and fell, giving the Cubs their fourth walk-off win this season.

The Cubs had bases loaded with one out in the bottom of the inning after Pirates right-hander Radhames Liz intentionally walked outfielder Jorge Soler.

"I told myself I've got to do it this time and I ended up doing the same exact thing," said Szczur, who flied out to Polanco in the 10th to start a double play.

But this time Polanco never had a chance at the ball after he skidded and fell.

"I couldn't believe it," Szczur said. "I crossed first base and thanked everybody, thanked God that this just happened."

The Cubs ran their winning streak to five while the Pirates dropped their third in-a-row.

The game, which lasted 5 hours and 1 minute, featured 21 combined runs and 30 hits while 16 pitchers were used.

The Cubs led most of the way until Pittsburgh forced a 10-10 ninth-inning tie on catcher Francisco Cervelli's two-out single that drove in third baseman Josh Harrison.

Starters Kyle Hendricks (Cubs) and Jeff Locke (Pirates) did not figure in decision.

Cubs right-hander Edwin Jackson (2-1) worked one inning for the win while Liz, who pitched just 1/3 inning, suffered the loss.

"We really should have put that away earlier," said Cubs manager Joe Maddon. "(But) we played really well today. We did not pitch well today, but we played a good game of baseball ... whether it was the at-bats, the hitting, the defense, the baserunning, everything.

"It would have really been a sin not to have won that game based on how well we played."

Rookie third baseman Kris Bryant broke a scoreless tie in the third, driving in center fielder Dexter Fowler and first baseman Anthony Rizzo with his fourth homer of the season.

Pirates first baseman Pedro Alvarez' solo homer broke the shutout in the fourth with his fifth homer.

The Cubs made it 5-1 in the bottom of the inning.

Fowler's one-out sacrifice to left drove in Hendricks, who reached on a lead-off double. Rizzo then hit his eighth homer of the year to left to bring home Fowler.

That was it for Locke, who threw 102 pitches in 3 2/3 innings. He was replaced by newly activated Antonio Bastardo, who closed out the frame.

The Cubs extended the lead to 7-1 as Pirates right-hander Rob Scahill allowed two runs in the fifth. Szczur's single to left drove in Castro and catcher Welington Castillo.

Locke gave up five runs on six hits, walked three and struck out four.

Cervelli doubled home three runs as part of a four-run Pirates sixth that right-handed reliever Justin Grimm gave up another as pinch hitter Corey Hart drove in Cervelli.

Center fielder Andrew McCutchen flew out to finally end the sixth.

Cubs right fielder Jorge Soler made it 8-5 in the bottom of the inning with a two-out single that scored Bryant from second. Rizzo's one-out base hit in the seventh drove home second baseman Addison Russell for a 9-5 lead while Bryant's sacrifice to deep center scored Fowler to make it 10-5.

But the Pirates weren't through as Harrison slammed a lead-off solo home run in the eighth off right-hander Jason Motte, cutting the Cubs lead to 10-6.

McCutcheon then hit his fourth home run of the season, a three-run shot off right-hander Pedro Strop that cut the Chicago lead to 10-9.

Pirates manager Clint Hurdle said he was encouraged by his team's comeback.

"There's positives to take out if this game all over the place," he said "You're looking at 7-1 down in the fifth inning. And you get the tying run on second base the go ahead in the sixth inning.

"Everybody in the lineup found a way to do something to help us get back in this game and give us an opportunity to win it."

NOTES: Pirates RHP Charlie Morton worked seven innings in a rehab start at Triple-A Indianapolis on Thursday. He allowed two runs (one earned) on 11 hits while walking none and striking out eight. He is due to arrive in Chicago on Saturday and could come off the 15-day disabled list this weekend. ... RHP Gerrit Cole (5-1, 2.32 ERA) goes against Cubs LHP Jon Lester (3-2, 4.10 ERA) in Saturday's middle game. ... Elias Sports Bureau reports that the Cubs' 6-5 win over the Mets on Thursday was just the third time in the last three seasons that the Cubs won a game after trailing by four or more runs. They were down 5-1 at one point. ... Cubs 2B Addison Russell saw his streak of 16 straight games reaching base safely come to an end in that Thursday game.