David Letterman David Letterman

David Letterman wants Brian Williams all to himself — or at least not share him with Jay Leno.

During the Williams' cross network appearance on CBS' Late Show Monday night, Letterman told the NBC Nightly News anchorman he doesn't like when Williams appears on Leno's Tonight show.

"I like to think of you and me as more real guys, as opposed to you and Jay," Letterman said, adding his Leno impression.

"And now you're sounding like him," Williams replied.

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Despite Letterman's ribbing of Leno about his plethora of cars, Williams played along well while still managing to remain neutral. Williams even tried to change the topic to Regis Philbin, but Letterman managed to quickly turn the conversation back to Leno.

"I'd really rather [Regis] spend more time with Jay," Letterman joked.