Sunday always had the potential to be an old-fashioned pitching duel.

Outside of one start this season, Freddy Peralta had been stellar for the Brewers and Javier Assad has been the Cubs second-best starter, behind Shota Imanaga, this season.

So, the Cubs offense was patient.

That perseverance paid off — and led to a 5-0 win over Milwaukee in the series finale at Wrigley Field. The Cubs took 2 of 3 from the Brewers and moved into a first-place tie atop the NL Central.

The Cubs had a clear plan off attack against Peralta — stay disciplined at the plate and see a lot of pitches. This season, opponents have a .350 batting average and .817 OPS against Peralta the third time seeing him in a game.

It worked.

The Cubs drew 6 walks against the righty, tied for the most walks he’s thrown in a game since his rookie season. That allowed the Cubs hitters to have a good look at him and work up his pitch count.

The Cubs drew 4 walks in the first 4 innings but couldn’t advance a runner past 2nd base. In the 5^th, Pete Crow-Armstrong had a 1-out single and Miguel Amaya was hit by a pitch, turning the lineup over. Nico Hoerner, with a third look at Peralta, deposited a double into the right-center gap to give the Cubs a 2-0 lead. Hoerner would score two batters later on a wild pitch.

Peralta’s day would be done after that inning, throwing 97 pitches and just 51 strikes.

“I mean, this is a player that historically … he doesn’t give up a lot of hits. So you got to just find your rallies when you can and we got a big hit with some guys on base,” manager Craig Counsell said after the game. “Nico got a big hit with guys on base. I thought [third base coach] Willie [Harris] made a great send there [with Amaya] and kind of sensed that really well.

“There has been some walks in there this year. He’s always been tough to get hits against really.”

The Cubs would add insurance runs on a solo home run from Dansby Swanson in the 6th and a Christopher Morel RBI single in the 7th. Swanson’s home run is a welcome sign for the Gold Glover.

He had been in a slump of late on both sides of the field, hitting .167/.231/.229 and had 2 errors over his last 15 games entering Sunday. 

“I think it a lot of it is just like a mentality, almost, where just a lot of the season — I wouldn’t say has been my best,” Swanson said. “And today was just kind of like be aggressive, go get it, kind of mentality. 

“And obviously that carries over offensively and defensively.” 

Assad, for his part, was as dominant as he’s been all season.

The righty tossed 6 shutout innings, allowing 3 walks and 4 hits with 4 strikeouts. His 1.66 ERA is tops among qualified National League starters and 4^th among all starters.

William Contreras had a 1-out double in the 1^st, advanced to third a batter later but was stranded by Assad. The Brewers didn’t have another baserunner advance past second the rest of the day.

Assad has been a revelation for the Cubs this season.

Entering Spring Training in a battle for the fifth starter role, Assad seemed to be an option to serve as the Cubs swingman. But, with an injury to Jameson Taillon in spring, another rotation spot opened up and Assad took the opportunity and ran with it.

“I feel great and happy with the results,” Assad said. “One of the things that I think has been helpful is I’ve been more stable in my mechanics. I think that’s helped me a lot to have location on my pitches and thanks to God things are working out and we’ll keep working hard so that we can continue.”

Assad has been not only one of the best pitchers for the Cubs, but in all of baseball for a rotation that has been stellar this season. The Cubs entered Sunday with the 4^th-best ERA from starting pitchers at 3.24.

That’s with the injury to Taillon delaying his start to the season, Opening Day starter Justin Steele being on the IL and Kyle Hendricks — their game two starter this season — sporting a 12.00 ERA and on the IL.

“We’re doing a good job,” Assad said. “We have a great pitching staff of starters and relievers. Honestly, you see how they throw and you yourself feed off each other. It’s really good to have a good team like that and to see your teammates do a good job.”

The rotation could take another step starting Monday, when Steele makes his first start back.

“I think that if anyone were to say by May 5, we’d have 21 wins, like I think most people would probably raise their hand and say, ‘Yes,’ right?” Swanson said. “It’s a testament just to our depth and the resiliency of this group. But we also know it’s a marathon, right? It’s a six-month season. It’s not a 35-game season; we got 147 more.

“We just got to kind of just stay with it, continuing to go on. We’ll obviously get some reinforcements with Steely and [Cody Bellinger] and Seiya [Suzuki], just some guys getting guys back — Merryweather — so things are looking up for us.”