The 48-year-old actress, who played Grace Adler on the NBC sitcom, asked fans to stop harassing Connick over his cheating character, Leo Markus, while appearing on the 49-year-old actor's talk show, Harry.
"I just want to make this perfectly clear -- he's not Dr. Leo Markus -- he's Harry fricking Connick fricking Jr.," she said in a mock PSA. "Please, America, it's time to let this go. Stop harassing Harry Connick, Jr. It wasn't real! Thank you."
Connick told Messing earlier in the episode that he got into "so much trouble, almost on a daily basis," for his character's infidelity. Grace and Leo split in Season 7 after Leo admitted to being unfaithful, but reconciled on the series finale.
"People would come up to me and say, 'How could you do that?'" Connick recalled. "'I'd say, 'Ma'am, I'm sorry, I don't know what you're talking about.' They'd say, 'You cheated on her.' This was years after. I'd say, 'Who did I cheat on?' They're like, 'You cheated on Grace.' I said, 'You know that's a TV show, right?'"
"People would come up to me and say, 'I hate Leo because of that.' Then they'd say, 'I hate Harry for that,'" Messing confirmed.
Connick said in an interview with People and Entertainment Weekly published Thursday that he hopes "Leo would've gotten smart and stopped cheating" today. Messing will next appear in ABC's upcoming Dirty Dancing remake.