6:42pm PT by Lesley Goldberg
'Big Bang Theory': Bob Newhart Goes Head-to-Head With Bill Nye (Video)
Newly minted Emmy winner Bob Newhart returns to CBS' The Big Bang Theory this week -- only this time, he's got company.
Bill Nye will make his debut on TV's No. 1 comedy Thursday when a scorned Sheldon (Jim Parsons) befriends "The Science Guy" when Newhart's Professor Proton asks Leonard (Johnny Galecki) for help with an experiment.
After Sheldon reveals he replaced his childhood idol with "a younger model," Professor Proton seems to feel pretty threatened, telling Nye -- who will play himself -- "Back off, bowtie!"
Newhart, who won his first-ever Emmy for his role on the nerdy comedy, told The Hollywood Reporter in September that he was already talking with producers about filming two more episodes.
Check out the clip, below, and hit the comments with your thoughts on the match-up. The Big Bang Theory airs Thursdays at 8 p.m. on CBS.