Sebastian Vettel shows no signs of letting up in his unstoppable march toward a fourth consecutive world title as he headed Red Bull teammate Mark Webber in Friday practice for the Japanese Grand Prix. Vettel can clinch the drivers’ championship this weekend with four races still remaining, if he takes the checkered flag and his nearest rival Fernando Alonso fails to finish in the top eight. After four successive race wins, the continuation of the German’s dominance of Formula One is now a mere formality.

Vettel was 0.168 seconds quicker than Webber, with the closest challenger to the Red Bulls, Mercedes’s Nico Rosberg a further tenth of a second back. Lotus pair Kimi Raikkonen and Romain Grosjean were next quickest ahead of Lewis Hamilton. Alonso could only come in 10th as he was one of a number of drivers to be caught out by the Suzuka circuit. The Ferrari man’s spin wasn’t nearly as bad as McLaren’s Sergio Perez, who was taken to the medical center as a precaution after crashing into a tire barrier.

Vettel survived the track’s difficulties, but is refusing to get complacent looking ahead to Saturday’s qualifying session.

“The car balance is decent, but I think we can still improve,” he said, according to “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. It’s good to see we are up there today, but it’s not always so important; we need to step up our game for tomorrow, as Mercedes will be strong in qualifying.”

Alonso, who lies a cavernous 77 points behind Vettel in the championship, had a hugely difficult day. Having had incidents in both sessions he failed to set a time that represented his true pace, but the fact that his teammate Felipe Massa could only come eighth quickest does not bode well for Ferrari, which has fallen further back of the front of the grid in recent races.

Mercedes looks to be the biggest threat to Red Bull continuing their domination into qualifying. However, Lewis Hamilton is aware of the familiar challenge that his team must overcome.

“This track is so beautiful to drive, it's fast and flowing, and our car really does feel good here,” he said. “But it's also a very unforgiving and challenging circuit; you're always on the limit so the trick is to balance and control that limit.  We've got some work to do this evening on the tire management in particular.”

Off the track, the paddock was rocked by the news that emerged during Friday afternoon’s practice that former test driver for Marussia, Maria de Villota, had been found dead in her hotel room in Seville. The 33-year-old’s fellow Spaniard Alonso described his shock.

“It’s hard to talk about Maria de Villota right now, as I had only just taken my helmet off, when I was told about her death and at the moment, I still can’t believe it and need a while to stop and think about it,” he said. “Of course, it’s very sad news for the world of motorsport as Maria was loved by everyone.”

Where to watch: Qualifying for the Formula One Japanese Grand Prix will get underway at 1 a.m. ET. Coverage will be provided by the NBC Sports Network, with a live stream available on NBC Sports Live Extra.