Matt Damon says Ben Affleck is 'fantastic' after rehab

— -- Matt Damon says his best friend, Ben Affleck, is doing "fantastic" following his stint in rehab for alcohol addiction.

During an appearance at CinemaCon in Las Vegas to promote his new film, "Suburbicon," on Tuesday, Damon told "Entertainment Tonight" that Affleck is "with the kids now" and "couldn't be happier."

Matt says Ben is "Mr. Mom-ing it right now," while his estranged wife, Jennifer Garner, is in Atlanta filming her upcoming movie, "Simon vs. the Homo Sapiens Agenda."

Affleck is "lucky" to be surrounded by such a solid group of guys, according to Damon. "I have a good group of friends ... we always keep track of each other and look out for each other."

Earlier this month, Affleck, 44, announced that he successfully completed a rehab program.

"I want to live life to the fullest and be the best father I can be," he said in a Facebook post earlier this month. "I want my kids to know there is no shame in getting help when you need it, and to be a source of strength for anyone out there who needs help but is afraid to take the first step."

"Suburicon," co-written and directed by another Damon pal, George Clooney, and co-starring Josh Brolin and Julianne Moore, opens nationwide in November.