Neil Patrick Harris Plays 'A Jackass' On Tonight's 'Glee'

'I certainly had a love scene offscreen with Sue Sylvester,' NPH jokes of getting close to the show's Cheerios coach.

On Tuesday night's (May 18) episode of "Glee," Will Schuester (Matthew Morrison) comes face-to-face with his onetime high school rival, Bryan Ryan. "How I Met Your Mother" actor Neil Patrick Harris guest stars in the role, flexing his singing muscle.

"Well, I'm on it," Harris told MTV News. "I sing a bit, and I'm a jackass. I sing a few [songs], one of which is 'Dream On' by Aerosmith. And yeah, that's me hitting the high note at the end, FYI."

In the episode, directed by Joss Whedon ("Buffy the Vampire Slayer"), Gleeks will learn what's at the root of the feud between the former classmates, and the revelation will be a surprising one, according to Harris.

But Harris isn't only fighting. He hinted there might be some loving too — with a certain head coach. "I don't know what scenes made it. I certainly had a love scene offscreen with Sue Sylvester, and that was exhausting," Harris joked. "But we'll see when we watch the show."

MTV News caught up with Morrison at the Fox upfronts in New York City on Monday, and though he wouldn't confirm the specific episode story line, he did admit that Jane Lynch, who plays Sue, was known to get frisky with her co-stars on set.

"Oh yeah! NPH! I actually haven't seen the episode so I don't know," Morrison said, referring to Harris. "This whole season has felt like one long episode, so it's kind of hard to think back and remember ... I don't know what's going to happen tomorrow night. I cannot confirm nor deny that, but Jane Lynch is known to do that. I might have done that as well."

Who do you think would win in a sing-off between Matthew Morrison and Neil Patrick Harris? Tell us in the comments!