Yes, the Chicago Cubs are having a heck of a time scoring runs lately.

But they also are having a heck of a lot of fun winning games.

The Cubs won another low-scoring, one-run game Sunday as they beat the Pittsburgh Pirates 3-2 in 10 innings in front of a Father’s Day crowd of 40,162. Ian Happ singled home Vidal Brujan for the game-winner to ignite an infield celebration.

The National League Central-leading Cubs (44-28) opened the series with a 3-2 victory Thursday, lost 2-1 in 10 innings Friday and won 2-1 on Saturday.

Those fans thirsting for the Cubs team that slugged its way to wins earlier in the season have had to settle for low-scoring nail-biters lately.

But the Cubs were glad to be able to take three of four from the Pirates after hitting .189 (24 for 127) in the series.

“You saw four or five balls today that would have been doubles or homers in other places,” Happ said. “You have to find ways to win that baseball game.”

The bottom of the 10th saw the seldom-used Brujan pinch-run for Justin Turner as the ghost runner on second. Kyle Tucker, who was given the day off from starting, pinch-hit for Reese McGuire and was intentionally walked.

While Happ got a lot of attention with the winning hit, he was quick to credit Brujan for leading a double steal to put runners on second and third with no outs and take the Cubs out of a potential double-play situation.

“Huge,” Happ said of the steal. “And it’s not easy for Brujan to do that — to come in the game and have the confidence to take that bag in that spot.

“It was massive. I can’t say enough about how tough that is for him to do that.”

Brujan said he spent most of the game trying to get ready in case he was called on.

“It’s my routine and something I’m used to,” he said through an interpreter. “I know it’s difficult, but I try to keep my body moving throughout the game.

“I try to walk around or pace around. I try not to sit down for too long or let my body cool down. I just move around and when I get called in, I’m ready to go in.”

Brujan, who had not played at all in the series until the pinch-running duty and has just 25 at-bats this season, was happy he could score the winning run and take part in the postgame merriment.

“It’s super fun and I’m super happy to be able to provide something for the team and we won,” he said. “It’s a step in the right direction going into this week.”

It was the Cubs’ fourth walk-off win of the season and the second off Happ’s bat. He singled to right on an 0-2 offering from reliever David Bednar (1-5).

“He threw two really good pitches to start that at-bat,” Happ said. “The first splitter was kind of straight down and the second one cut. I was looking for something up enough and that one was.”

After the first inning, it looked like a slugfest was in store.

Pirates starter Mitch Keller hadn’t won since picking up a victory in his season debut March 28 in Miami, losing nine games. He entered with the lowest run support in the majors with the Pirates scoring just 2.08 runs per game in his starts.

They gave him two runs in the first, but he didn’t hold the lead as Seiya Suzuki grounded out to drive in Happ and Dansby Swanson singled home Michael Busch in the bottom half.

Suzuki broke a tie with Pete Crow-Armstrong for the team RBI lead with 58.

That was all the scoring until the 10th.

Cubs starter Colin Rea settled down after giving up the two first-inning runs and threw five shutout innings after that.

Four relievers shut down the Pirates (29-44) over the last four innings, not allowing a hit. Chris Flexen (5-0) picked up the win and hasn’t allowed an earned run in 18 1/3 innings.

Injury updates

Left-handed starter Shota Imanaga will make a rehab start Friday for Triple-A Iowa against Nashville. He has been on the injured list since May 5 with a left hamstring strain.

He threw four innings and 44 pitches Saturday in an Arizona Complex League game and another 11 pitches in the bullpen. He’s expected to throw another bullpen session early this week before heading to Nashville.

Right-hander Eli Morgan, who is on the 60-day IL with an elbow impingement, threw one 15-pitch inning in the same game, striking out two, and threw five more pitches in the bullpen. No timetable was set for his next round of work.

Jeff Vorva is a freelance reporter for the Chicago Tribune.