MILWAUKEE — Plastic sheets have been hanging from the ceiling of the visitor’s clubhouse at American Family Field all weekend. The champagne and beer were there somewhere as well, but never put on ice. It will all travel with the Mets to Atlanta. The Amazins’ have a chance to clinch a postseason berth with one win over the Atlanta Braves in Monday’s doubleheader at Truist Park. Had the Arizona Diamondbacks lost again, the doubleheader would have been unnecessary, but the Snakes (89-73) beat the San Diego Padres 11-2, forcing the NL East rivals to play again Monday. The Braves (88-72) lost to the Kansas City Royals, 4-2. One more win, and the Mets are in. “We’ll be up for the challenge,” said manager Carlos Mendoza. “We’ve been through a lot before and this is not going to stop us.” The Mets are in this position because of Francisco Lindor and David Peterson. A big day at the plate for the team leader and seven shutout innings on the mound by Peterson led the Amazins’ to a 5-0 win over the Milwaukee Brewers on Sunday afternoon. Lindor went 2-for-3 with a home run, two RBI, two stolen bases, two runs scored and a walk, playing through back pain. Peterson gave  the Mets some much-needed length, Francisco Alvarez went 2-for-3 with two RBI and a run and Jose Iglesias extended his hitting streak to 20 games. It’s a less-than-ideal scenario for all involved, but the Mets can take solace in the fact that their team leader appears to be healthy enough to produce at a critical time. “He was Francisco Lindor today,” Mendoza said. Facing right-hander Colin Rea, Lindor led off the game with a walk. He promptly swiped second base and moved to third on a ground ball by Iglesias. Brandon Nimmo singled up the center to drive in Lindor, giving the Mets their first lead in a week. “I thought it was important putting the pressure on them right away,” Mendoza said. “Lindor gets on and steals that base right away on first pitch. I thought it was big.” Lindor slid into home plate head first and was slow to get up. The pain in his back grabbed at him and Mendoza briefly worried before seeing him get up and head back to the dugout with ease. It subsided. “I’m pretty sure he was feeling but then it goes away,” Mendoza said. “He’s grinding, man, he’s a ballplayer. He knows how important he is, and we saw it today. I don’t think we saw any hesitation.” Rea managed to strand two to end the inning, but the Mets continued to apply pressure. They put runners on in the second, forcing him to pitch around traffic. They put one on in the third. Finally, they cracked him in the fourth, scoring twice to go up 3-0. J.D. Martinez snapped his 0-for-35 streak at the plate with a double that bounced off the third-base bag in the fourth. Starling Marte moved him over with a sacrifice bunt, putting him in position to score on Alvarez’s single to left field. The ball was just deep enough that left fielder Isaac Collins couldn’t throw out Martinez, a slow baserunner, at home. Tyrone Taylor then hit one down the third base line to bring up Lindor with two on and one out. He delivered, lining a splitter to right field to score Alvarez. After going up 4-0 in the fifth, Lindor led off the sixth with a home run to right. His 32nd of the year might have been his biggest to date. Rea (12-6) allowed five earned runs on 10 hits, walked three and struck out five over 5 2/3 innings for the Brewers (93-69), who could face the Mets again Tuesday in the first round of the postseason. Peterson was stellar, holding the Brewers to only one hit and it didn’t even leave the infield. He walked three and struck out eight in the win (10-3). With 18 innings to play Monday and a bullpen short on manpower, those seven innings felt bigger than usual. “Not only did he give us seven, it was seven quality innings,” Mendoza said. “I thought he threw the ball really well. He got strike 1, stayed on the attack, he was aggressive. I liked the tempo — just everything. He was in complete control of that game, and we needed that.” Milwaukee tried to rally for a tie in the first inning, putting runners on the corners. But with two outs, Peterson got Eric Haase to swing through a slider to end the inning. The lefty cruised through the next six innings, facing only two more baserunners. “I was just trying to give the team everything I had and keep us in a spot where we could win the ballgame,” Peterson said, The Brewers put two on against Phil Maton in the eighth, but the right-hander got out of it, leaving the ninth for closer Edwin Diaz, who pitched around a man on second to preserve the win. “With the way we started the year, nobody expected us to be in this position,” Mendoza said. Here we are with a chance to do something special.”