"It's not feeling great, but it's not feeling bad," Thompson said after Thursday's practice at Emerson College in Boston. "It's like somewhere in between. It's like 60 percent -- nah, 70."
Thompson, who finished with a season-high 39 points against the Pacers, was walking under his own power with a bit of a limp after the game, though the team said X-rays were negative. He has been rehabbing the injury since.
"He's obviously out there getting some shots up, shooting around, but it'll likely be a game-time decision [against Boston]," Warriors interim head coach Luke Walton said. "If there's any concern at all that his ankle's hurt, then we're not going to play him."
When asked for his prognosis, Thompson said: "I'm optimistic about life and Friday. And, yeah I'm optimistic. I think if I have a good shootaround [on Friday], I'll play."
Thompson indicated that the decision to play against the Celtics is complicated by the Warriors playing the Milwaukee Bucks on a back-to-back Saturday.
"It is the team's call, and if it's not 100 percent Friday, I might have to sit out because we have such a quick turnaround," Thompson said. "I want to finish the trip on a high note in Milwaukee."
Thompson has recently rehabbed back soreness that plagued him earlier in the season.
"I had no back pain for the last couple weeks, and it feels great," he said.
Of the newer ankle injury, Thompson said: "It's just a very minor set back. I won't be out very long."