Rehabbed Ben Affleck To Attend Matt Damon's Wild Birthday Bash In Vegas: 'He Thinks He's Okay To Party'

Matt Damon is planning to ring in another year with a birthday bash in Las Vegas this weekend, and RadarOnline.com has learned exclusively recently-rehabbed BFF Ben Affleck may be attending the wild night.

Insiders reveal the birthday boy and his crew are worried the boozehound actor is going to be the party pooper at the Friday night bash in Sin City, where the big UFC fight — Khabib vs McGregor — is also going down.

"Ben's invited," continued the source, "but it's more like they're trying to dis-invite him."

"He thinks he's okay to go to the party," said the source. "It's been planned for months, way before his stint in rehab.

"But those who are going to Vegas for Matt are concerned. They think Ben will blow all the fun because everyone will be so focused on him, if he's doing okay — and if he's drinking."

So friends are hatching a plan to keep the Batman star in Los Angeles.

"The plan is to tell Jennifer not to let him go," the source told RadarOnline.com exclusively. "They are hoping, like before, she will lay down the law and he'll listen."

As RadarOnline.com readers, Affleck faced a huge setback in August when his estranged wife Jennifer Garner drove him to rehab after a much-needed intervention.

The troubled Daredevil star, 46, has struggled with sobriety for years, reportedly going in and out of treatment three times and receiving outside guidance from sober coaches over the years.