SUZUKA (AFP) - Briton Jenson Button showed hell make German Sebastian Vettel work for his second world championship by topping the timesheets in both practice sessions at the Japanese Grand Prix on Friday. The 31-year-old McLaren driver, after leading morning practice, set his benchmark time of 1min 31.901secs with 31 minutes remaining in the 90-minute afternoon session at Suzuka. The 2009 world champion is 124 points adrift of Red Bull's Vettel with five races remaining in the season, meaning he needs to win all five Grands Prix -- and Vettel to finish no better than 10th in any race -- to deny the German back-to-back titles. Vettel, who crashed out in the final stages of the morning session, was third in afternoon practice, 0.194secs off top spot. He needs only one point to seal the world driver's crown. Splitting the only two men in mathematical contention for the title was Spaniard Fernando Alonso, who finished 0.174secs behind Buttons session-best time for Ferrari. Australian Mark Webber was fourth for Red Bull, while Alonsos Ferrari teammate, Brazilian Felipe Massa, was fifth. German pair and Mercedes team-mates Michael Schumacher and Nico Rosberg were sixth and seventh ahead of Briton Lewis Hamilton, who finished eighth and 1.344secs behind team-mate Button for McLaren. Russian Vitaly Petrov (Renault) and Swiss Sebastien Buemi (Toro Rosso) rounded out the top 10. In sunny but windy conditions at Suzuka, Alonso led for much of the first half of the later session before team-mate Massa jumped to top spot after 43 minutes on the softer Pirelli tyre. Alonso quickly deposed the Brazilian by three-tenths of a second on the softer tyre before Button took over at the top with his session-best lap. Vettels best chance of edging ahead of the McLaren driver was thwarted by yellow flags at turn eight after the Williams of Venezuelan rookie Pastor Maldonado ground to a halt with an engine problem with 30 minutes remaining. It was a disastrous session for Williams, with Brazilian Rubens Barrichello crashing at turn eight halfway through the session. The 39-year-old veteran, who is yet to be confirmed by the British team for next year, dropped his left rear wheel onto the grass under braking and ended up in the barriers. Barrichello, who won the Japanese Grand Prix in 2003 for Ferrari, finished the session in a lowly 18th place. Barrichellos compatriot Bruno Senna was one of the few other drivers to have an off-track excursion in the 90-minute session; the Renault driver spun at turn one after 30 minutes and ended up in the gravel trap, but was pushed back onto the track by circuit marshals. Local Japanese favourite Kamui Kobayashi survived a couple of lurid moments, including one where he was sideways through the 300km/h Turn 16, to post the 16th-fastest time for Sauber.