The former Boston Celtics' little scoring machine will not, however, play his second game with the Cavs when his new team invades TD Garden for the second meeting of the season between last year's Eastern Conference finalists.
Thomas will be with the Cavs and has asked the Celtics not to give him a video tribute, a wish granted by Boston with the thought that could come in the future -- like Feb. 11 when Cleveland returns on Paul Pierce jersey retirement day.
Without Thomas, the Cavaliers went 24-12. With him they're 1-0.
"They're the team to beat. Everybody knows that," Celtics coach Brad Stevens said Wednesday. "... They haven't even had Isaiah yet. We all know how special he is.
"I can't say enough positive, glowing things about Isaiah. He's a special guy."
Thomas, welcomed by the Cleveland crowd when he entered the game off the bench, played 19 minutes Tuesday. He scored 17 points on 6 of 12 from the floor, 3 of 8 from 3-point range. He was 2-for-4 from the foul line, had three assists and was a plus-17.
"It was a special night for me," Thomas said. "I haven't played in seven months, so to be able to be out there and compete against another team was special. Obviously to get the win was even bigger but just to be able to compete, to be out there and be in an arena setting, a game setting ... it was a great feeling for myself."
"It was great," LeBron said on television after the game. "Just to see him, his first basket, he had his pull-up shot going a little bit.
"It's a spark and jolt we need on our team right now."
The Cavs defeated the Celtics (30-10) on opening night, Boston going through the trauma of losing Gordon Hayward, probably for the year, less than six minutes into his Celtics career. With Thomas out of this Wednesday night picture, the James-Kyrie Irving "reunion" again takes center stage.
"I don't think anybody on this team has any type of fear," Boston's Jaylen Brown said. "I think everybody's even-keeled about this game. I think we think we're a better team. And we just want to come out and show it."
James, asked about what needs to be done with Thomas' return, said, "It doesn't matter. Just give him the ball."
With Thomas coming off the bench, he, Dwyane Wade, Kyle Korver, Tristan Thompson and Jeff Green were a combined plus-92 Wednesday night.
Thomas' hip injury has drawn all kinds of attention in recent months, leaving his return -- and whether or not he will be his former self, something that has to be determined.
"We really don't know. We know he's excited to once again grace an NBA floor and actually play," James said. "We're excited for him as teammates as well.
"We expect him to be gassed. We expect him to just be very emotional about the whole, just his journey, just getting back. As far as his performance, that's the last thing that we're thinking about."
Also returning to TD Garden Wednesday is Jae Crowder, another part of that mega deal that brought Irving to Boston -- and Crowder expects some love from his former home crowd.
Gary Washburn of the Boston Globe spoke with Crowder and tweeted, "(Celtics) fans have cheered for opposing team's players before (i.e. Gordon Hayward), I feel like they should do the same for me because I gave them a lot. I hope they give me a little cheer."
Crowder, seeing that as a slap at him, was upset with the way Celtics fans cheered for Hayward when he came to town with the Utah Jazz last season.
The Cavs are deep -- and are still missing the rehabbing Derrick Rose and Iman Shumpert, who are working their way back.
Playoff series aside, the Cavs have won six of the eight games between the teams over the last two-plus seasons. The Celtics and Cavaliers split two games in Boston last season before the Cavs took the Eastern Conference finals in five games.