All eyes were on Red Bull's Sebastian Vettel to see if he could defend the title he won in 2010 and 2012, in the face of stiff competition from teammate Mark Webber, Ferrari's Fernando Alonso and McLaren's Jenson Button and Lewis Hamilton. In the year that sees five former World Champions competing against current back-to-back World Champion title holder for the ultimate prize, and the introduction of revised regulations aimed at closing the gap.