A brutal Broadway riff-off between Neil Patrick Harris and James Corden ended in an embarrassing moment for the former, as he split his pants open on "The Late Late Show" Monday night.

While Corden was addressing the audience during the show, NPH walked out and interrupted the host with an unexpected challenge.

"We have a score to settle and it's about Broadway," the former "Hedwig and the Angry Inch" star said. "I see you going around, hosting the Tonys, acting like you're the only TV star who can sing Broadway shortness. Some of us, dude, have actually won a Tony."

When Corden pointed out that he too had one, Harris pointed out it was only "for a non-singing role. Burn."

The two then went head-to-head in a "Broadway musical riff-off," trying to one-up each other by singing show tunes from shows like "Gypsy," "Les Miserables," "Chicago" and "Hedwig."

After Corden gave Harris the win, the two teamed up for an impressive rendition of "My Shot" from "Hamilton."

While audiences didn't catch Harris' embarrassing moment when it happened, the actor revealed he had a minor accident while performing "Sugar Daddy" after Corden pointed how he changed pants when he re-emerged on stage for an interview.

"When I went down on my knees there, I had a nice wardrobe malfunction and split my pants from my ass to my knee," he confessed. "I left it all on the stage for you."

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