Kellan Lutz knocked out one of his 'Twilight Saga: Eclipse' co-stars on set.

The stacked actor, who plays vampire Emmet Cullen in the 'Twilight' films, has revealed he accidently punched his fellow actor Jackson Rathbone - who plays his adopted vampire brother Jasper Hale - leaving him unconscious while shooting a fight scene for the third movie in the franchise.

Speaking at the official 'Twilight Saga: Eclipse' press conference in London yesterday (01.07.10), Kellan said: "We had fun times with the fights scenes. We had an oopsy daisy moment when I hit Jackson and knocked him out a little bit during one of our scenes."

Director David Slade quickly corrected the 25-year-old model-turned-actor, saying: "You knocked him completely out!"

Kellan replied: "He was a trooper he got up and started gurgling his words and mumbling - it was cute. He has become a mischievous little Jackson lately, who thinks he can take the world. But it was really great times after that."

Last night, thousands of fans turned out for the premiere of 'Eclipse' in London's Leicester Square.

A host of cast members dazzled on the red carpet, including Kellan, Ashley Greene, Nikki Reed and 'Eclipse' newcomer BooBoo Stewart.

However, main stars Robert Pattinson, Kristen Stewart and Taylor Lautner did not make an appearance on the red carpet leaving many 'Twilight' fans disappointed.