"It's obviously more serious than we thought," Indians manager Manny Acta said. "When something like that happens, you think it's only going to be a day or two. He didn't feel much pain [Saturday]."
Sunday's news changed that.
"We don't know if it's season-ending yet, but surgery is possible," Acta said. "If he does come back, it could be the last month of the season."
Choo, seen wearing a protective wrap on his right hand Sunday morning, will be evaluated by specialist Dr. Tom Graham on Tuesday. He joins shortstop Asdrubal Cabrera and center fielder Grady Sizemore on the DL.
"I've dealt with injuries before in this job, but this is kind of weird, because those are our three best players," Acta said. "Nobody is feeling sorry for us. Other guys have to step it up."
The Indians recalled outfielder Michael Brantley from Triple-A Columbus on Sunday to assume Choo's spot on the active roster. Brantley will step in as the Tribe's everyday center fielder and leadoff hitter.
"We have to move on with the young kids," Acta said. "Now, we don't have to wait until Spring Training to see what these guys can do. It will give us more clarity."
Choo, the top candidate to represent the Tribe in the All-Star Game on July 13 before Friday's injury, leads the team in batting average (.286), home runs (13), RBIs (43) and on-base percentage (.390).
"I feel sad for the kid," Acta said. "It's tough for the club, but mainly for him, because he was having a good season."