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Colin Firth, Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by Jonathan Short/Invision/AP)
LONDON—In the trailer for their new movie "Gambit," Britain's Colin Firth and American co-star Cameron Diaz are shown in various states of undress. But the two say fans shouldn't get the wrong idea—"Gambit" is a caper film, not a love story.

Speaking at the comedy's world premiere in London on Wednesday night, Diaz said flesh was only flashed for laughs in the film.

Firth agreed. Referring to a scene where he appears without trousers, he said audiences will get "treated" to 20 minutes of his knees, but that's all.

Directed by Michael Hoffman, "Gambit" is about private art curator Harry Deane (Firth) who devises a scheme—with the help of a Texas rodeo queen (Diaz)—to con England's richest man into purchasing a fake Monet painting.

Cameron Diaz and Colin Firth arrive for the World Premiere of Gambit at the Empire cinema in central London, Wednesday, Nov. 7, 2012. (Photo by Joel
Cameron Diaz and Colin Firth arrive for the World Premiere of Gambit at the Empire cinema in central London, Wednesday, Nov. 7, 2012. (Photo by Joel Ryan/Invision/AP) (Cameron Diaz and Colin Firth arrive for the World Premiere of Gambit at the Empire cinema in central London, Wednesday, Nov. 7, 2012. (Photo by Joel Ryan/Invision/AP))

"Gambit" opens in the U.K. on Nov. 21.

Alan Rickman arrives for the World Premiere of Gambit at the Empire cinema in central London, Wednesday, Nov. 7, 2012. (Photo by Joel Ryan/Invision/AP)
Alan Rickman arrives for the World Premiere of Gambit at the Empire cinema in central London, Wednesday, Nov. 7, 2012. (Photo by Joel Ryan/Invision/AP) (Alan Rickman arrives for the World Premiere of Gambit at the Empire cinema in central London, Wednesday, Nov. 7, 2012. (Photo by Joel Ryan/Invision/AP))

Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by Jonathan Short/Invision/AP)
Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by Jonathan Short/Invision/AP) (Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by Jonathan Short/Invision/AP))

Alan Rickman, left, Colin Firth and Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by
Alan Rickman, left, Colin Firth and Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by Jonathan Short/Invision/AP) (Alan Rickman, left, Colin Firth and Cameron Diaz seen at Meet the Filmmakers: Gambit at The Apple Store on Wednesday, Nov. 7, 2012, in London. (Photo by Jonathan Short/Invision/AP))