Justin Timberlake at Keep A Child Alive's 5th Annual Black Ball at Hammerstein Ballroom - arrivals, New York City, USA - 131108

The pop hunk made a surprise cameo on Saturday's (15Nov08) show, slipping into a figure-hugging leotard to dance with Knowles in a sketch.

He and Saturday Night Live regulars Andy Samberg and Bobby Moynihan mimicked Beyonce's choreographed routine, but failed to make the final cut as her backing dancers.

The Bootylicious singer later performed her new track Single Ladies, with the real dancers.

Actor Paul Rudd also appeared on the show, to promote his new movie Role Models.

Source: WENN