CHICAGO -- Freddy Peralta held off a suspension long enough to pitch in the Brewers’ biggest series of the season so far, but Round 1 of this rivalry went to the Cubs.

With Peralta’s five-game suspension on appeal for at least one more day, Chicago touched him for three runs during a 33-pitch fifth inning to turn a scoreless afternoon into what became a 5-0 Brewers loss at Wrigley Field on Sunday.

It was a disappointing end to what was an important day for Peralta, who was loathe to miss the first Brewers-Cubs matchup of 2024. He is the Brewers’ unquestioned ace with Corbin Burnes traded and Brandon Woodruff out for the season, and going into Sunday’s rubber match against the Cubs, the Brewers were 6-0 in Peralta’s starts.

“Really important,” Peralta said. “Especially today, because I had the opportunity to win this game and win the series.”

Instead, the Cubs (21-14) took two of three for a virtual tie with the Brewers (20-13) atop the National League Central standings and, for the first time in 2024, dealt Peralta a defeat. His previous starts had been all team victories, including an 8-2 victory over the Rays last week at American Family Field in which Peralta was ejected after hitting Jose Siri with a pitch during a tense night twice delayed by disputes.

Now, Peralta confirmed he’ll probably drop his appeal. He would serve his suspension from Monday-Friday and line up to start Saturday against the Cardinals at home.

That gap means the Brewers will need a sixth starting pitcher this week, and the leading contender is left-hander Robert Gasser, their No. 5 prospect, per MLB Pipeline. Gasser, who would be the 10th pitcher to start a game for Milwaukee before the season’s first quarter is complete, might have been up before now had he not been sidelined in Spring Training by bone spurs in his elbow.

Gasser started Sunday for Triple-A Nashville and got his pitch count up to 78 over four innings, departing with a lead.

“I think there’s a chance you might see him,” Brewers manager Pat Murphy said. “You see the hole there with Freddy being down, right? That would be a strong candidate.”

While the Brewers continued to cobble together a starting rotation around him, Peralta played the role of ace once again until things started to go wrong in the decisive fifth. Pete Crow-Armstrong started the Cubs' rally with a one-out infield single and stole second before a two-strike fastball clipped No. 9 hitter Miguel Amaya on the elbow guard.

Nico Hoerner followed with a double to the right-center-field gap which was good for two runs because center fielder Blake Perkins was shaded the other way and then briefly bobbled the baseball. After a groundout pushed Hoerner to third, Peralta threw a wild pitch that made it 3-0.

“The hardest part about this is I was putting zeros on the board. That’s what I try to do,” Peralta said. “Then everything changed quick.”

Two more walks in the inning pushed Peralta’s total to six free passes in the game, matching his career high from his second MLB start at Minnesota in 2018.

“[Command] wasn’t that bad, but I walked a lot of people today. It shouldn’t have happened,” Peralta said. “I have to be better than that.”

The Brewers’ offense will be better, Murphy said. They didn’t score a run against any of the three Cubs starting pitchers in 18 1/3 innings. Murphy called it a learning experience for the six hitters in Sunday’s lineup who, as of the start of this year, had less than a year of Major League service time -- or none at all.

"It's kind of in their DNA to never beat themselves,” Cubs shortstop Dansby Swanson said of the Brewers. “They pitch. They play great defense. They obviously run the bases well. They just do a lot of the little things right. … I thought we had to play a good brand of baseball this weekend to be able to beat them, and we were able to do that two out of three times."

For the newest Brewers hitter, No. 4 prospect Tyler Black, it was the first visit to the Friendly Confines. After going 1-for-12 in the series while hitting in the three-hole, he was asked for his takeaway from the past three days.

“The only thing that matters is winning,” Black said. “Obviously thrown into the fire; I wouldn’t want it any other way. I really felt the intensity and I’m looking forward to the future of that.”