Mar.8 (GMM) Christian Horner and Bernie Ecclestone have singled out Jenson Button as potentially the biggest rival to Red Bull's dominance in 2012.
"Jenson seemed to get the team around him and strung a set of results together that was very impressive," Red Bull team boss Horner told Sky Sports.
And when pressed on BBC radio to name Vettel's biggest rival, he admitted: "Probably Jenson."
F1 chief executive Ecclestone, meanwhile, tipped 32-year-old Button to give Hamilton yet another headache in 2012.
"Jenson looks after the car and tyres better, so it is more than likely he will be a big problem for Lewis," he told the Sun newspaper.