Former Nets coach Lawrence Frank is in the mix to replace Tom Thibodeau as Celtics coach Doc Rivers' top assistant.

Frank joined the Celtics to watch Tuesday's summer league loss to the 76ers. Rivers acknowledged that Frank is an impressive candidate for the vacancy.

Thibodeau left Boston to coach the Bulls earlier this offseason.

"It's going good, I'm in no rush, and it's really not going to be a big deal," Rivers said. "Lawrence is one of the guys I am looking at, and we're looking at a couple of other guys, but I don't think it will be very hard to find a guy.

"Lawrence Frank is a great defense guy, but he knows the game. I want to get a guy like that who does everything."