The comedian topped tonight's public vote with his homage to Christopher Walken's appearance in Fatboy Slim's 'Weapon of Choice' video, while Whitbread's performance to 'You Should Be Dancing' by the Bee Gees was favoured by judges Russell Kane, Jo Brand and Lee Nelson, aka Simon Brodkin.
The Gadget Show pair Suzi Perry and Ortis Deley, who danced to 'Livin' la Vida Loca' by Ricky Martin, also finished in the top three of the vote, but were snubbed by the panel.
Patrick Monahan's impression of Rihanna, and Watson and Oliver's rollerskate routine to Torvill and Dean's 'Bolero' also failed to impress.
Rivron, Whitbread and The Cuban Brothers will compete against Tyger Drew-Honey and Dani Harmer, Omid Djalili, Eddie 'The Eagle' Edwards, Miles Jupp, Terry Alderton and the team of Laurie Brett and Tameka Empson in next week's final.
The Let's Dance for Sport Relief winner will be decided when the show returns to BBC One on Saturday, March 17 at 7.10pm.