SAO PAULO, Brazil - Red Bull will set its sights on Formula 1's other two top drivers - Fernando Alonso and Lewis Hamilton - if Sebastian Vettel switches to Ferrari.That's the claim of the team's owner,l Dietrich Mateschitz, responding to rumours that German Vettel would seek a new challenge after achieving so much with Red Bull.VETTEL FOR FERRARI 'ONE DAY' In a rare interview about F1, on the eve of Vettel securing his third consecutive Drivers' title, Mateschitz told Salzburger Nachrichten that the 25-year-old was "one of the three best drivers" on the grid. Referring also to Hamilton and Alonso, Mateschitz said Vettel "is the youngest of the three, and definitely there is potential for further development"."Perhaps he is near his zenith in terms of speed but with more experience he can certainly keep getting better and better," he insisted.Mateschitz played down rumours that Vettel was toying with a switch to Ferrari. "There are not only contracts, but he is bound to us as well through loyalty and friendship but that doesn't exclude that he gets offers from other teams,."Fascinatingly, he even said he could understand Ferrari's lure. "If I were a driver I would probably enjoy the thought of driving for Ferrari one day as well. It's not only natural, but quite legitimate."If he should ever leave us, we would wish him well, and then nothing would stop Alonso or Hamilton driving for us."