Matthew Perry is opening up about the unusual lengths he went to in order to convince former girlfriend Julia Roberts to guest star on “Friends.”

In his forthcoming memoir “Friends, Lovers and the Big Terrible Thing,” Perry said Roberts agreed to appear on a 1996 episode of “Friends” titled “The One After the Superbowl: Part 2” only if she could work alongside him. Getting her to fully commit to the role of Susie Moss ― the childhood classmate of Perry’s character, Chandler Bing ― would require some extra persuasion on his behalf.

“Julia had been offered the post-Super Bowl episode in season 2 and she would only do the show if she could be in my story line,” the actor recalls in the book, as seen in an excerpt that appeared this weekend in the U.K.’s The Times. “Let me say that again — she would only do the show if she could be in my story line. (Was I having a good year or what?) But first, I had to woo her.”

As far as the “wooing” was concerned, Perry first sent Roberts “three dozen roses” along with a note that read: “The only thing more exciting than the prospect of you doing the show is that I finally have an excuse to send you flowers.”

Still, the “Pretty Woman” star wasn’t completely sold ― at least not yet.

“Her reply was that if I adequately explained quantum physics to her, she’d agree to be on the show,” Perry said. “Wow. First of all, I’m in an exchange with the woman for whom lipstick was invented, and now I have to hit the books.”

So the actor gave himself a crash course, and fulfilled Roberts’ request by submitting a lengthy, expeditiously researched “paper all about wave-particle duality and the uncertainty principle and entanglement.” And the result? “Not only did Julia agree to do the show, but she also sent me a gift: bagels — lots and lots of bagels,” he said. “Sure, why not? It was Julia fucking Roberts.”

Roberts was apparently moved by the gesture, and the two actors struck up a friendship that involved a lot of correspondence via fax machine before shooting the episode. By the time they arrived on the “Friends” set to film “The One After the Superbowl, Part 2,” they were happily an item.

In a Hollywood Reporter interview last year, “Friends” executive producer Kevin Bright and staff writer Alexa Junge both corroborated Perry’s scientific paper claim. Junge also hinted that Roberts was already interested in Perry “from afar” long before they worked together.

“There was a lot of flirting over faxing,” she explained. “She was giving him these questionnaires like, ‘Why should I go out with you?’ And everyone in the writers room helped him explain to her why. He could do pretty well without us, but there was no question we were on Team Matthew and trying to make it happen for him.”

Unfortunately for Perry and Roberts, their romance was short-lived. Elsewhere in “Friends, Lovers and the Big Terrible Thing,” Perry said his own insecurities about dating one of the world’s most revered stars turned out to be a major obstacle.

“I had been constantly certain that she was going to break up with me,” he wrote, according to the Times. “Why would she not? I was not enough; I could never be enough; I was broken, bent, unloveable. So instead of facing the inevitable agony of losing her, I broke up with the beautiful and brilliant Julia Roberts.”

“Friends, Lovers and the Big Terrible Thing” is due out Oct. 28.