Lewis Hamilton kept Ferrari’s Formula One championship leader Fernando Alonso off the top of the timesheets in Friday’s first free practice for the Korean Grand Prix.McLaren’s Hamilton needs a win on Sunday to get back into a title fight that looks increasingly like a duel between Alonso and Red Bull’s Sebastian Vettel, and the Briton lapped the dusty Yeongam circuit with a best time of one minute 39.148 seconds.Alonso, four points clear of reigning champion Vettel with five races remaining, was 0.302 slower with Red Bull’s Mark Webber third fastest ahead of Ferrari’s resurgent Felipe Massa.Vettel was fifth fastest while Lotus’s Kimi Raikkonen, having his first taste of the track some 400km south of Seoul due to his absence from Formula One for the past two years, ended up 11th.The Finn was trying out a new ‘Coanda’ exhaust system that his team hope will bring big benefits in the closing races as they battle Ferrari for third place in the constructors’ standings.