Emmy winner Bob Newhart returns to The Big Bang Theory on Thursday night.

According to The Hollywood Reporter, Newhart will battle it out with Bill Nye the Science Guy, who makes his first appearance on the show.

In the episode, Sheldon (Jim Parsons) seeks refuge in Bill Nye when Professor Proton (Newhart) asks Leonard (Johnny Galecki) to do so. Feeling threatened, Professor Proton, tells Bill Nye to “Back off, bowtie!“

Newhart recently won his first Emmy for Best Comedy Guest Actor after 52 years of acting. He received to a standing ovation.

The Big Bang Theory airs Thursday nights on CBS.