Bulls coach Fred Hoiberg said before the game that Butler developed some swelling in his knee after Sunday's practice and didn't do much during Monday's shootaround. It remains unclear exactly how long Butler will be out.
"We'll know more [Tuesday] on how he's feeling," Hoiberg said after the game. "Dr. [Brian] Cole did look at him and said structurally everything looks OK. Now it's a matter of how he's feeling in the morning. If that swelling goes down, we'll put him in a compression [sleeve] overnight and all day tomorrow, see how he's doing and then make a determination on what the treatment is."
Hoiberg said that at this point, no MRI is scheduled, but that could change after Butler is checked out Tuesday.
"We're going to see how he reacts to the treatment tonight and [Tuesday] and then make a decision," Hoiberg said.
Hoiberg said after Sunday's practice that Butler was feeling "great," so his absence came as a surprise to a team that was finally getting back to full strength -- aside from Joakim Noah, who is out for the year after shoulder surgery.
"Obviously, there's concern," Hoiberg said before the game. "Jimmy's a warrior. He's going to try to play through anything. He just developed swelling around that knee, and he's got a lot of soreness in there. So [it's] just too early to tell how long this one will be. He's optimistic he'll be back soon in talking to him, and I'll never doubt him."
Hoiberg is hopeful his team will be able to bounce back, even as the injury bug bites yet again. The issue for the Bulls is that although they were able to beat the Bucks, it will be very difficult for the group to sustain itself without Butler if he has to miss a long stretch.
"[Butler] was moving around, he was a little stiff, as expected, had a little bit of soreness in his back as he said he always does," Hoiberg said. "He works out so hard, but you get that first game action, he just had a little bit of stiffness in his back. He was moving around pretty well [Sunday], but as the night went on and came in this morning, he didn't do much at shootaround -- more due to the back than anything. And then [the knee] just kind of swelled up."
Butler's setback was the latest in a string of injury woes for the Bulls. Then reserves Aaron Brooks (right patellar tendinitis) and Bobby Portis (left orbital contusion) were forced from Monday's victory due to injuries.
Veteran Mike Dunleavy, who missed most of the year after offseason back surgery, tried to keep a sense of humor as he discussed what has happened to this team.
"At this point, it's borderline comical," Dunleavy said. "We just can't stay healthy for whatever reason. It's unfortunate. It's disappointing, but it is what it is. So we got to continue to battle with who's out there, and we will."
Information from The Associated Press was used in this report.