After New York roughed up rookie right-hander Mike Fiers in the series-opener, Marcum takes the mound opposite Jenrry Mejia, who will make his first start in exactly two years after undergoing Tommy John surgery on his right elbow. Mejia made one relief appearance this season, tossing two innings in which he allowed a solo home run to Dan Uggla in a 3-0 loss to the Braves on Sept. 7.
"I won't be nervous now, because I did it before," Mejia said. "If this was my first time here, I'm going to be nervous.
"It's different now because I have a little bit more control of my pitches. Before, I threw like, 'Strike, strike.' But now, I'm thinking about, 'Where am I throwing it -- inside, outside?'"
Mets manager Terry Collins echoed Mejia's confidence, noting how the 22-year-old right-hander was "pretty stinkin' good" with "electric stuff" when he saw him pitch two years ago.
Across the dugout, Milwaukee is embracing its turn of fortune as a benefit of MLB's new playoff format, which features two Wild Card teams playing in a one-game series. The Brewers enter Saturday 3 1/2 games behind the Cardinals for the second Wild Card spot, though they trailed by as many as 7 1/2 games on Sept. 1. Over its past 24 games, Milwaukee is 18-6.
An additional boost of confidence could come from the return of first baseman Corey Hart, who has been sidelined since Sept. 9 by a foot injury. Hart is second on the team with 27 home runs and third with 77 RBIs, and the Brewers are hoping he'll be available off the bench beginning on Saturday.
"I've been scoreboard watching probably since we were 10 games out," Hart said. "I'm one of those guys. I catch myself being very optimistic all the time. Even before I got hurt, I'm out there taking ground balls and I'm looking up there at all the different scores. Now that I'm not playing, I'm in here a lot checking scores."
Mets: Valdespin to get more chances at the plate
With the Mets taking a long, hard look at several of their young prospects after falling out of postseason contention, Collins says Jordany Valdespin is due to receive more at-bats in the final weeks of the season.
The Mets have thus far been pleased with Valdespin's production at the plate in limited opportunities. The 24-year-old rookie is batting .247 (43-for-174) with eight home runs -- five in pinch-hit appearances -- and 26 RBIs in 83 games.
"One of the things I'm seeing is that he's going up there now with a little bit better game plan," Collins said. "When he first got up here, he was coming right out of the gates swinging like crazy and had some great success.
"Now they've changed the way they pitch to him, and I think he's starting to make some adjustments. I'm going to hope that as we get near the end of the season, that he continues to get better at it."
Brewers: Marcum looking for first win since returning from DL
After spending two months on the disabled list with stiffness in his surgically repaired right elbow, Marcum is winless in four starts since his activation. He'll take the mound with an extra fifth day of rest since the Brewers were off on Thursday.
Marcum hasn't lasted more than 5 2/3 innings in any of his four starts since rejoining Milwaukee's rotation on Aug. 25. Over that span, the 30-year-old right-hander is 0-1 with three no-decisions and a 5.03 ERA over 19 2/3 innings pitched. Marcum also surrendered two home runs in each of his two most recent starts, and the Brewers have managed just one win in those four starts.
"Marcum, the first inning [his] command was all over the place," Brewers manager Ron Roenicke said after Marcum's last start, a 5-4 loss to the Cardinals on Sunday. "After that, he settled down."
After wrapping up their current homestand on Sunday, the Brewers will take their final road trip of the season with a total of 10 games in Pittsburgh, Washington and Cincinnati.