The Milwaukee Brewers will have to try and get back to the playoffs without their MVP.
Yelich will travel back to Milwaukee on Wednesday for further evaluation, general manager David Stearns told reporters, according to Todd Rosiak of the Milwaukee Journal Sentinel.
"We don't have a definitive time frame (for his return), other than we know that he'll be out for the remainder of the season right now," Stearns said. "We also don't know whether surgery is required. He'll need some further diagnostic imaging tomorrow in Milwaukee, then (he'll) meet with our doctors and plot a plan going forward."
The 27-year-old sustained the injury when he fouled a pitch off his knee during his first-inning at-bat. He was able to walk off the field under his own power but only did so after spending several minutes on the ground in obvious pain.
"This is a gut punch," Stearns added.
Manager Craig Counsell said Yelich was "crushed" upon hearing the diagnosis, according to MLB.com's Christina De Nicola.
"We feel awful for Christian," Counsell said. "He's a special player and it's a joy to watch him play every day. ... Not being able to see that every day is definitely no good."
The injury ends what has been an incredible season for Yelich, who was following up last year's MVP-winning campaign with an even better 2019. He ends his season having hit .329/.429/.671 with 44 homers, 97 RBIs, 29 doubles, 30 stolen bases, and 7.7 WAR. He currently leads the NL in OBP, slugging, OPS, and WAR.
Yelich stole three bases to clinch the 12th 40-30 season in MLB history this past weekend.
Despite losing Yelich, the Brewers beat the Marlins 4-3 to move within 1 1/2 games of the rival Chicago Cubs for the second NL wild-card spot.