VIDEO: Andy Karl & ROCKY Cast Perform 'Keep on Standing' on 'Letterman'

Andy Karl and cast members from Broadway's Rocky performed the number 'Keep on Standing' on last night's Late Show with David Letterman on CBS. The musical just received four Tony Award nominations including Best Lead Actor in a Musical for Karl. Check out the appearance below!

ROCKY officially opened at Broadway's Winter Garden Theater on March 13, 2014. The original musical brings to life the iconic and inspiring story of struggling small time Philly boxer, RockyBalboa, who gets a once-in-a-lifetime shot to go the distance against heavyweight champ Apollo Creed. Both an adrenaline-infused spectacle and a surprising story of blossoming romance between two lonely outsiders, Rocky is a heart-stopping and viscerally theatrical new musical for everyone brave enough to follow their dream.

Produced on a shoestring budget, the original 1976 film, Rocky, was shot in 28 days, and starred its young and then-unknown screenwriter, Sylvester Stallone. Like the character of boxer Rocky Balboa, Stallone had to fight the studio, which wanted more bankable stars like Ryan O'Neal or Burt Reynolds, to be cast in the role. Stallone's performance would earn him an Academy Award nomination for Best Actor and launch his career as one of Hollywood's biggest stars. The small underdog film went on to become an American film classic, winning the 1977 Academy Award for Best Picture, and launching one of the most successful and iconic characters in Hollywood history.

ROCKY features an original score by Stephen Flaherty and Lynn Ahrens, the celebrated Tony Award-winning and Academy Award-nominated songwriters behind Ragtime, Once on This Island, and Anastasia, and a book by multiple Tony Award-winner Thomas Meehan (The Producers, Hairspray, Annie) andSylvester Stallone, who was nominated for an Academy Award for Best Original Screenplay for the 1976 Oscar-winning Best Picture, Rocky.

The production is directed by Alex Timbers, the Tony-nominated director behind the acclaimed musicals Here Lies Loveand Bloody, Bloody Andrew Jackson, as well as Peter and the Starcatcher, which continues to run off-Broadway. The musical features choreography by Steven Hoggett, who received a Tony Award nomination for his work on Once and Kelly Devine, best known for the long-running Broadway hit Rock of Ages.

The Rocky cast features Andy Karl (Rocky), Margo Seibert (Adrian), Terence Archie (Apollo Creed), Dakin Matthews(Mickey) Danny Mastrogiorgio (Paulie), Jennifer Mudge (Gloria) and ensemble members Adrian Alfredo Aguilar, Eric Anderson, Michelle Aravena, JAmes Brown III, Sam J. Cahn, Vincent Corazza, Kevin Del Aguila, Ned Eisenberg,Bradley Gibson, Stacey Todd Holt, Sasha Hutchings, David Andrew Macdonald, Vasthy Mompoint, Vince Oddo,Okieriete Onaodowan, Adam Perry, Kristin Piro, Luis Salgado, John Schiappa, Samantha Shafer, Wallace Smith,Jenny Lee Stern, Dan'yelle Williamson and Mark Zimmerman.