The Cubs hold a five-game lead with nine days left in the regular season after winning their second straight tense game over the Brewers. Milwaukee dropped into third in the division, 5 1/2 games behind Chicago, after St. Louis beat Pittsburgh earlier Friday.
The Brewers had the tying run at first with one out in the bottom of the 10th, but Eric Sogard was called out at second trying to advance on a ball in the dirt. Shortstop Addison Russell appeared to hold the tag as Sogard's foot lifted off second for a split-second, and the call was confirmed on review.
What started as a rebuilding season in Milwaukee is ending with a postseason push that has defied expectations.
But the Brewers' hopes for a division title took another hit after another loss in 10 innings to the reigning World Series champions.
Knebel (1-4) took the loss after allowing three walks and two hits over two innings. Carl Edwards Jr. (5-4) got the win with 1 2/3 innings of scoreless relief.
Stephen Vogt and Brett Phillips hit back-to-back homers in the second for Milwaukee. Leadoff hitter Jon Jay went 2 for 5 with two runs and an RBI for the Cubs.