Ibaka injured the ankle in Monday's Game 5 blowout loss to the Celtics.
"I'm just trying to see how I feel tomorrow," Ibaka said.
Ibaka added that he felt he could have continued to play on the ankle in Game 5, but it felt different when he woke up Tuesday morning.
Toronto is officially listing Ibaka as questionable for Game 6.
However, Toronto coach Nick Nurse said the team is optimistic that Ibaka will be able to go.
"We'll just wait and see on that. But same as always, if he's there, we'll play him. I think there's a good chance of that," Nurse said. "If not, we'll move on to the next guy and get them ready to go."
Raptors guard Fred VanVleet said Ibaka is a "big part of the team" and, like Nurse, said he thinks Ibaka will play on Wednesday.
"Obviously we need him out there," VanVleet said. "I haven't spoken to him about how he's feeling or anything, but just knowing him personally, I would be surprised if he wasn't out there. Serge is probably the best I've ever seen at taking care of his body and recovering and following his routine. Hopefully he can get back feeling good today and be ready for us tomorrow."
Ibaka is averaging 11.8 points and 6.6 rebounds per game against Boston this series while shooting 51.2% overall and 50.0% from 3-point range. He also had three 20-point games in the Raptors' first-round sweep against the Brooklyn Nets.
Boucher has played 24 minutes over three games this series. Hollis-Jefferson has played twice for a total of nine minutes, although all of those came in the final minutes of out-of-hand losses in Game 1 and Game 5.