David Letterman wants Jay Leno as a guest on his show, to combat new "The Tonight Show" host Jimmy Fallon's soaring ratings, according to the New York Daily News.

"There's been quiet talk behind the scenes for months that Dave will have Jay Leno on as a guest," one insider said. "(Letterman's) producers waited until Fallon debuted (on 'Tonight'), give him space out of respect, but are now ready to pull out all the stops."

That's right. Let loose the late night Kracken.

Leno and Letterman were longtime friends who had a famous falling out when Leno scored "The Tonight Show" hosting spot over Letterman when Johnny Carson retired in 1992. But the pair reportedly recently talked on the phone for 20 minutes and smoothed things over, the source said.

Letterman initiated contact, hoping to mend a relationship that got so heated, it was documented in the book and movie "The Late Shift."

Letterman ended up with CBS' "Late Show" and fought Leno for guests and ratings for two decades.

In his first week, Fallon's viewership was double Letterman's, which definitely got the attention of Letterman's people.

"The audience will definitely shrink down to a more normal size in a few weeks, especially after the Olympics are over" and the Fallon "Tonight" loses its new shine, one TV insider says.

"Fallon was also promoted constantly and the biggest entertainment news around .... so millions more people have been tuning in this week out of curiosity."

Representatives for Leno and Letterman didn't return the Daily News' calls for comment.

Sources told the paper Leno isn't looking to hurt his successor, just trying to stay relevant.

The booking battle is about to heat up, said another source.

"Letterman's booking department is keeping track of everyone who has appeared on Fallon so far, and considering if they're worth having" the source says. "Letterman's people aren't taking the leftovers."

So far, Letterman hasn't turned down any big names who have visited Fallon.

"Somehow I don't think Dave would turn away Jerry Seinfeld," the source said. "Jerry was a guest on Fallon's second night."

Contact Tony Hicks at Facebook.com/BayAreaNewsGroup.TonyHicks or Twitter.com/insertfoot.