John Mayer -- Prepare to be Mind Blown, Regis!

John Mayer is a big star. Regis Philbin has met lots of big stars. Regis A) doesn't recognize John and B) is genuinely star struck when Bob Saget clues him in.

The singer was at Craig's with Saget when the famous TV host made his way into the restaurant and ran into the duo outside.

It's actually pretty cool ... Mayer introduces himself to Regis and says they've never met.