Button heads Hamilton in Japan practice

Britain\'s Jenson Button headed his departing McLaren team-mate Lewis Hamilton in opening free practice for the Japanese Grand Prix on Friday. In fine and sunny conditions, Button, 32, who has started from pole position just once this season, clocked a time of one minute 34.507 seconds in the 90-minute session to lead the 24-car field. Second fastest was Hamilton, who this week announced he will move to Mercedes for the 2013 season. Hamilton was 0.233 seconds slower than Button but one-tenth quicker than Australia\'s Mark Webber in his Red Bull. Fourth fastest was Nico Rosberg, who pulled his Mercedes to a stop at the trackside in the last minute. His team-mate Michael Schumacher, the seven-time world champion who announced his retirement Thursday, placed fifth. Sixth was local favourite Kamui Kobayashi in the Sauber, followed by Brazil\'s Felipe Massa in the first of the Ferraris. Force India duo Paul di Resta and Nico Hulkenberg finished eighth and ninth respectively while Venezuelan driver Pastor Maldonado completed the top 10 in his Williams. Current world championship leader Fernando Alonso of Ferrari was 11th with his nearest challenger in the title race, Red Bull\'s Sebastian Vettel, 17th.