The Cubs have been playing a ton of close games lately.

And David Ross’ squad has found a way to win a vast majority of those.

After splitting with the White Sox last week at Wrigley Field, the Cubs grinded out back-to-back series victories over the Royals and Tigers and have played 9 straight games decided by 2 or fewer runs.

They continued the trend Thursday night in Pittsburgh, pulling out a 5-4 victory in 10 innings over the Pirates.

Ian Happ drove home a pair of runs with a soft liner in the top of the 10th inning to break a 3-3 tie.

Adbert Alzolay closed it out in the bottom half of the 10th for his 20th save of the season.

“Phenomenal, phenomenal character win,” David Ross told reporters in Pittsburgh. “Good job by the bullpen. … Good team win.”

The Cubs opened up a 3-0 lead when — who else? — Cody Bellinger singled home a run with 2 outs in the top of the 1st inning. Then they rallied in the 2nd for a pair of runs on a Jeimer Candelario sacrifice fly and Nico Hoerner 2-out single.

Initially, it didn’t look as if starter Justin Steele would to be able to provide the Cubs much length as his pitch count was rising in the early innings. But he settled in and managed to turn in a quality start — 3 runs, 2 earned in 6 innings.

He got into some self-induced trouble in the 2nd inning by walking the leadoff batter and then letting a tapper back to the mound by him. He struck out the next 2 batters but then Pirates center fielder Ji Hwan Bae singled through the infield for his team’s first run.

In the 3rd, Steele gave up a long homer to Joshua Palacios that splashed into the Alleghany River beyond the right field fence.

“He locked it down after that. Nice job,” Ross said of Steele. “That’s what we’re expecting him to do. He’s at that level now. He’s our horse, we’re gonna lean on him. Did a nice job to give us 6 and turn it over to the bullpen.”

With the Brewers idle on Thursday, the Cubs gained a half-game and now sit 3 games back in the National League Central. They also retain their hold on the 2nd Wild-Card spot.

The Cubs will send Kyle Hendricks to the mound on Friday against Pirates ace Mitch Keller. Coverage begins on Marquee Sports Network at 5 p.m.