SUZUKA, Japan -- Sebastian Vettel was fastest in the second practice at the Japanese Grand Prix on Friday, indicating he's on track to clinch his fourth Formula One championship this weekend.
Vettel was 0.168 seconds faster than Red Bull teammate Mark Webber around the Suzuka circuit. Mercedes driver Nico Rosberg was two tenths of a second off Vettel.
"The car balance is decent, but I think we can still improve," Vettel said. "Looking after the tires will be important here, especially during the race. The car works fine at the moment, but we need to make sure we set it up the right way."
Vettel has won three of the past four races in Japan and can clinch his fourth successive world title in Sunday's race. The title will be his if he wins and nearest rival Fernando Alonso finishes ninth or worse.
Webber, who will leave F1 after the season, is hoping for better luck at Suzuka after his car burst into flames at the Korean GP last Sunday.
"We've done a lot of laps today and will now work on tomorrow," Webber said. "The track is a special one and in terms of difficulty, it's right up there. We have to be very accurate and if you're not, then you get penalized."
Lotus driver Kimi Raikkonen, who had a mid-session spin, was fourth fastest, followed by teammate Romain Grosjean.
Mercedes driver Lewis Hamilton, who was fastest in the morning session, was sixth ahead of Toro Rosso's Daniel Ricciardo. Ferrari's Felipe Massa was eighth while McLaren driver Jenson Button, who won the Japanese GP in 2011, was ninth.
There were numerous incidents in the afternoon practice.
Alonso lost control of his Ferrari at the Degner curve and finished 10th. McLaren driver Sergio Perez spun off the track and slammed into a tire wall sideways but could be heard over the team radio saying he was fine, and finished 16th.
Williams driver Pastor Maldonado also hit the tires just 12 minutes into the session.
Jules Bianchi sat out the afternoon practice after running off the track early in the first practice and colliding head-on into a tire wall. The Marussia driver was unhurt but was unable to take part in the afternoon session as his chassis was not repaired in sufficient time.