The incredible story of how David Letterman saved Conan O'Brien's career in 1993

Conan O'Brien paid tribute to David Letterman Tuesday night ahead of the veteran host's final show on Wednesday.

O'Brien said Letterman has "been the north star for me and every comic of my generation" and told a fascinating personal story about how Dave once saved his career.

"What I wanted to talk about tonight, briefly, is something incredible that Dave did for me almost 22 years ago," O'Brien began. "Something that had a profound impact on my life."

"Some of you may be too young to know this, but way back in 1993, I took over David Letterman's iconic 'Late Night' television show."

"I was a complete unknown, with absolutely no experience performing on television. I was utterly and totally unprepared for that enormous job," O'Brien explains. "I don't even think anything like that could happen today. We can check people out on YouTube today, but then, I was a complete unknown and totally unprepared."

"After going on the air in September 1993, I got the s--t kicked out me," he continued. "Critics despised me, the ratings were bad, my skin broke out - which it hadn't done since high school and then again at this crucial time. And my network started to make it clear that I probably wouldn't be around for very long. I honestly have no ill will about that time, because by and large people were right. I'm serious, I was in way over my head."

"The conventional wisdom was that everybody thought I should be cancelled. And then something miraculous happened," says the now 52-year-old. "After four dreary months, out of the blue, we got a message at the show that David Letterman wanted to come on the program as a guest."

"Now understand, Dave wasn't just the biggest late night star at the time, he was the biggest thing on television. He didn't go on other people's shows. It was like The Beatles asking Maury Povich if they could stop by and sing a couple of tunes."

"It was that absurd! And at the time, I was convinced it ws a prank. I didn't think it could be real," said O'Brien.

"But on February 28, 1994, David Letterman walked onto my set and blew the doors off the place. It's easily one of the happiest nights of my professional life."

"True story, after that one night, that one appearance, everything turned around for me," claims O'Brien, who now has his own TBS late night show.

"The morale of the staff shot through the ceiling, my producer, writers, Andy, we all thought that if David Letterman can come on our show and say a few kind works, then maybe, just maybe, we can earn the right to be here."

"And we survived."

"So, the point behind all of this is that I just want you to know, that if you have ever liked any silly or stupid thing I've done on television over the past 20 years, you must know that it probably never would have happened if it weren't for Dave."

"At one of the lowest points of my life, when I was a 30 year old national punch line, Dave, for reasons I still don't really understand - completely rescued me."

"I still believe that that simple act of kindness turned everything around and made all the difference."

Watch Conan's full farewell tribute below: