In upcoming HBO drama film Confirmation, about the contentious hearings of Supreme Court Justice Clarence Thomas in 1991, Greg plays Vice President Joe Biden, who was a senator at the time.

Speaking about getting into character, the actor told The Tonight Show starring Jimmy Fallon that while filming he injured the same tooth that had been bothering Biden during the hearings.

"During these confirmation hearings he had a terrible tooth ache, and while we were making the movie, I went to watch a movie one afternoon myself when I wasn't working," he told Jimmy on Tuesday night (05Apr16), adding, "And I'm watching the film, having a little popcorn, and I suddenly realise my tooth is missing."

Greg, 52, was astonished by the coincidence that it was "the very tooth" or back molar that had plagued Biden, and compared the event with something that would happen to Daniel Day-Lewis, who is renowned for his method acting.

During an earlier appearance on America's TODAY show on Tuesday, Greg also admitted he was a little anxious to tackle such a well-known public figure as Biden, though the hairstylists on set helped him capture the "follically-challenged" political figure through various hairpieces and costuming which gave him confidence.

"He has a certain sound though, certainly a certain presence," he told the daytime show. "His DNA is well known to people so I was a little nervous to take on the role."

Confirmation, which depicts the controversy that unfolded when Thomas' legal assistant Anita Hill came forward to say she was a victim of his sexual harassment, also stars Kerry Washington as Anita, Wendell Pierce as Clarence, as well as Erika Christensen, Jennifer Hudson and Eric Stonestreet in supporting roles.

The film is set to air in the U.S. on April 16 (16).