"Something like that was so different," Rivers said before Thursday's game against the Brooklyn Nets. "This will just be more fun because I know Paul and Kevin, I know how competitive they are. It will be a lot of fun."
For the first time since all three left Boston in the offseason, Rivers will coach against Garnett and Pierce. Rivers coached Pierce for nine seasons, and Garnett for six. The trio won an NBA title in 2008.
"Me and Kevin and Paul we talk so much," Rivers said. "It will be different than last night. I haven't coached against them in quite a while so it will be different. That will be strange."
The trio were supposed to clash on Nov. 16 in Los Angeles, but Pierce and Garnett did not play because of injury. The Clippers won that game, 110-103. Thursday will instead mark the first time Rivers coaches against them since his days as Orlando's coach in 1999-2003.
Pierce and Garnett, who were instrumental in the Celtics' success during Rivers' tenure, are experiencing disappointing seasons. Garnett is averaging just 6.7 points and 7.6 rebounds, and Pierce, who will come off the bench in consecutive games for the first time his career, has battled injuries and is averaging just 11.9 points.
Rivers said coming off the bench doesn't matter to Pierce.
"I don't think he cares. Paul's a ball player, he doesn't care. If I asked Paul last year to come off he would have," Rivers said. "Paul just wants to play basketball. He's going to play it more than this year. He's a professional scorer, he's still trying to get healthy, he's not 100 percent. I don't think Paul minds one way or another."
" Rivers said it was "disappointing" that Nets assistant Lawrence Frank was reassigned to writing daily reports. Frank served as an assistant under Rivers in Boston.
"It's disappointing, quite honestly, because I'm a friend of both and I just wish they could have figured it out," Rivers said.
" Rivers would not be in favor of the NBA getting rid of its divisions.
"I don't think they should," Rivers said. "I think it would be hard to do. Obviously you look at it this year and say 'Wow, it'd be nice to have the top 16 teams or whatever it is in there.' I don't know. This has been going on for a while. At the end of the day, I think it's fine. It's the way it is now. It won't be this way forever. I wouldn't like that."