Milwaukee pulled within four games of Chicago for the second NL wild card. The Cubs, who had won their last six road games, remained 2 1/2 back of NL Central-leading St. Louis, which lost 9-4 at Pittsburgh.
"It's a really important game for us," Yelich said. "We'd really like to win three of four. I think that would be a good goal going into the series. But, we've got to win tonight to do that, then you've got to worry about tomorrow and keep going. It's no secret, we've got a lot of ground to make up and we're running out of time to do it."
Yelich went 0 for 5 in Milwaukee's 10-5 loss in the series opener Thursday night.
"If he has a rough game, something really good is probably going to happen the next day," Brewers manager Craig Counsell said. "That's why he's a great player. He doesn't let these things last. He makes adjustments really well, he knows himself really well."
Yelich had the big blow in the Brewers' four-run third inning, hitting a three-run drive to right-center. Cory Spangenberg added a run-scoring bunt single off Cole Hamels, giving Milwaukee a 4-1 lead.
Davies (9-7) allowed one run -- Nicholas Castellanos' 24th homer in the third -- and three hits in his first win since July 18. The right-hander went 0-5 with a 7.76 ERA in his previous six starts.
Davies almost picked up a win in his previous outing, but he was pulled after pitching 4 2/3 innings in the Brewers' 2-0 victory over the Cubs last weekend.
Hamels (7-6) was tagged for five runs and nine hits in 3 1/3 innings.
"It's the pitches before (the home run), allowing the two guys on and just not executing against those guys," Hamels said. "When you get into that sort of situation, it definitely kills the rally. Any momentum that we were able to get from the previous half-inning, and then for them to get it back, it's not what you want to do."
Castellanos' homer was his 13th in 33 games since he was acquired from Detroit at the trade deadline.
"The at-bat by Yelich just kind of flipped the whole thing," Cubs manager Joe Maddon said.
Cubs: All-Star SS Javier Baez was scratched with lingering soreness in his left thumb. He will get an MRI on Saturday and likely will not play that day, Maddon said. ... Closer Craig Kimbrel said he hopes to return next week. He was placed on the 10-day injured list Thursday with elbow inflammation, retroactive to Monday. "It's frustrating, very frustrating," he said.
Brewers: C Manny Pina, who left Thursday's game after taking a foul ball off the mask, suffered a concussion, Counsell said. He will miss at least a couple of games. C Jacob Nottingham was recalled from Triple-A San Antonio. ... 3B Mike Moustakas missed his third consecutive game because his sore left hand is "not making great progress," Counsell said.
Cubs: RHP Yu Darvish (5-6, 4.25 ERA), who missed his last turn with right forearm tightness, makes his first start since Aug. 27. He has 78 strikeouts and just three walks in his last 10 starts.
Brewers: LHP Gio Gonzalez (2-2, 4.14 ERA) is making his fifth start of the season against the Cubs. He went 1-0 with 1.40 ERA in his previous four starts against them.
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