TIFF 2014: Potentially awkward celebrity run-ins to look out for at this year's festival

The Toronto International Film Festival kicks off today, and while celebrities will be heading to T.O. in droves over the next week, they might not all be happy to see each other.

Mark Ruffalo should probably watch his back this year, because one of his former friends will be circulating at the same parties. In town to promote "Infinitely Polar Bear" and "Foxcatcher," Ruffalo recently claimed that his relationship with Jennifer Garner (which formed when they starred together in the 2004 rom-com "13 Going on 30") was nixed by her husband, Ben Affleck.

"We have a great time together," Ruffalo said on "Watch What Happens Live" in June. "But then Ben came on the scene." (When host Andy Cohen said, "I heard he doesn't allow her to have male friends," Ruffalo simply shrugged.)

With Garner planning to attend the fest to promote Jason Reitman's "Men, Women & Children," it's possible that her hubby will be joining her. We imagine Ruffalo will be on the other side of town the night Affleck arrives.

Speaking of Garner, she will no doubt be avoiding filmmaker Kevin Smith's "Tusk" premiere at TIFF this year. Smith's friendship with Ben Affleck goes back to their 1995 film "Mallrats," but the director recently admitted their bromance ended when Affleck married Garner.

"He's got a wife that don't care for me at all," Smith told Yahoo Movies in July. "And plus, honestly, he probably don't care for me at all anymore. He's a triple-A-list movie star and s--- like that."

Also in July, Smith had reportedly explained on his Silent Bob Speaks tour that his jokes rubbed Garner the wrong way.

"Jennifer does not share the same sense of humor as me — she did not like my jokes," Smith said. "I was picking on Ben Affleck making fun of him because I've known him for a really long time — I was talking smack — and Jennifer goes, 'You know, if you keep saying stuff about him, I'm going to kick your ---.'"

Exes who are probably planning to avoid each other include Jake Gyllenhaal (who will be promoting "Nightcrawler") and Reese Witherspoon (who is set to walk the red carpet for "The Good Lie" and "Wild"). The two actors reportedly dated from 2007 to 2009 after meeting on the set of "Rendition."

Not to mention former partners Diane Keaton, who will attend TIFF for "Ruth & Alex," and Al Pacino, who is also set to appear for "Maglehorn" and "The Humbling." The famous duo reportedly had an off-on again relationship while they were working on "The Godfather" trilogy together.