Not even the 2017 Oscars could result in a truce between these two Hollywood stars.
What came next was a new chapter in this famous—and dare we say hilarious—feud.
"Tonight, in spirit of healing and bringing people together, I would like to bury the hatchet with someone I've had issues with. I would. Matt Damon," Jimmy began during his opening monologue. "I've known Matt for a long time now. I've known Matt so long, when I first met Matt, I was the fat one, okay? It's true. And we've had problems. He's a selfish person. Those of you who have worked with him know this. But Matt did something very unselfish and I want to commend him for it."
He began to share how Matt allowed Casey Affleck to star in Manchester by the Sea, which ultimately became an Oscar-nominated performance.
"He handed an Oscar-caliber role over to his friend and made a Chinese pony tail movie instead," Jimmy joked. "And that movie went on to lose $80 million. Smooth move, dumb ass. See? It's so easy to reach out and heal."
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Later on in the show, Jimmy allowed a few special tourists including Gary from Chicago to experience the live show. When introducing Casey to the visitor, Jimmy said, "Ignore the jerk behind him." That "jerk" was Mr. Damon.
In the third hour of the show, Jimmy looked back at Matt's role in We Bought a Zoo. While showcasing scenes from the flick, Jimmy shared witty (and sarcastic) thoughts on his enemy's role. "He has almost no discernible talent," Jimmy joked. "But he works."
Soon after, Matt would appear on stage to serve as a presenter with Ben Affleck. Unfortunately, every time Matt tried to say a word, the music began playing him off. "Wrap it up!" Jimmy joked from the audience. "We want to go home!"
Before the final award was handed out, Jimmy had one final jab directly towards his friend.
"And now, my favorite part of the night is here. A chance to see Matt Damon lose an Academy Award," the host joked. "Here to present our final Oscar on the 50th anniversary of the great movie Bonnie and Clyde, please welcome Warren Beatty and Faye Dunaway."
What a night for you Matt.
There were plenty of signs that something funny could be happening at the 89th Annual Academy Awards. Just a few days ago, Jimmy headed to Matt's seat inside the venue and had some fun with his seat sign. "Best Picture Vominee Matt Damon #Oscars," the Jimmy Kimmel Live! host wrote on Instagram while drawing on Matt's face.
In a separate interview, Jimmy joked that he really hopes the producer doesn't win for Manchester By the Sea.
"I'm going to do everything I can to make sure that he doesn't win or doesn't know that he won," Jimmy joked to The Hollywood Reporter. "My goal is to keep him offstage."
Hate to say it Jimmy, but the feeling may be mutual. "I don't think I need to do anything to make his performance worse," Matt shared with E! News' Marc Malkin. "He's gonna be really terrible no matter what."
The feud is still young. We still have the post-Oscars special of Jimmy Kimmel Live!
Watch E!'s live 2017 Oscars red carpet coverage starting at 9:30 a.m. on Monday, Feb. 27. And catch our Fashion Police special Tuesday, Feb. 28, at 7:30 p.m.