Lewis Hamilton fired a warning shot to world championship leader Fernando Alonso on Friday, clocking the fastest time in the first practice at the Korean Grand Prix. The McLaren man, who is fourth in the drivers' standings, forty-two points behind the Ferrari of Alonso, was 0.302 seconds faster than the Spaniard, who was second quickest under cool but sunny conditions. Hamilton, who will quit McLaren for Mercedes next season, badly needs a win on Sunday to stay in the championship hunt. Sebastian Vettel, second in the overall standings going into the race in Korea, was fifth-fastest, 0.940 seconds off Hamilton's time of one minute 39.148 seconds. Vettel's Red Bull team-mate Mark Webber registered the third fastest time of the session, followed by Alonso's Ferrari team-mate Felipe Massa. The Mercedes of Michael Schumacher and Nico Rosberg came home with the sixth and seventh best times respectively at a sparse Korea International Circuit in Yeongam. Much-maligned Frenchman Romain Grosjean, who incurred the wrath of the Australian Webber last week in Japan after they collided, clocked the eight-fastest time.text here