Knebel was walking with a limp Friday, a day after he was injured while pitching against St. Louis.
"Right from the start I kind of thought it was pretty serious, the way it felt," Knebel said. "Then once I got home I started to kind of realize it doesn't feel as bad. I knew if it was torn off the bone I wouldn't be able to do anything, so it definitely was a little bit of a relief."
Knebel had a 1.78 ERA and 39 saves in 45 chances last year, supplanting Neftali Feliz as closer in early May. Knebel struck out 126, tying Boston's Craig Kimbrel for the most among major league relievers, and set a big league record by opening the season with at least one strikeout in 45 consecutive games.
Knebel blew a save chance on opening day, struck out the side in getting a save at San Diego the following day, then didn't get in a game up Thursday. He entered in the ninth inning with the Brewers trailing by six runs.
He retired Addison Russell on a flyout, hit Javier Baez with a pitch and gave up a home run to Jason Heyward. After striking out Ian Happ, Knebel fell to the ground on a 1-0 pitch to pinch-hitter Tommy La Stella.
"We'll see how it progresses," Brewers manager Craig Counsell said. "We feel like we're fortunate. We know we're going to have this guy pitching for us again for a good chunk of the season."
Milwaukee recalled right-hander Adrian Houser from Double-A Biloxi.
Counsell wasn't ready to say who will close.
"Who we're playing and lineups may have a little bit to do with that," he said. "But I think as we get further along in this somebody will probably claim most of the opportunities."
Jeremy Jeffress converted 27 of 28 chances in the first half of 2016, was traded to Texas and then was dealt back to Milwaukee last season.
Milwaukee's bullpen entered Friday with a 2.01 ERA.
"We've got a bunch of guys pitching well down there," Counsell said. "Their jobs are the same and that's to come in and get the hitters they're facing out. We get hung up on what number inning they're coming in."
Milwaukee was also without outfielder Christian Yelich, who was out of the lineup for the second straight game because of a sore oblique.