Vettel title bid hit by mechanical woes
Red Bull driver Sebastian Vettel of Germany drives his car during the qualifying session ahead of the Formula One Japanese Grand Prix in Suzuka on October 12, 2013
Vettel, 26, will join Michael Schumacher and Juan Manuel Fangio as only the third driver with four straight if he wins at Suzuka and his nearest rival, Fernando Alonso, is outside the top eight.
The race will be preceded by a minute's silence after the death on Friday of former reserve driver Maria de Villota, 33, a year after she sustained serious head injuries in testing.
Vettel has won the last four races and eight out of 14 this season to open up a 77-point lead in the championship with five grands prix remaining, including Sunday's event in Japan.
But the young German's bid for a fifth straight pole position at the Suzuka circuit was hit by the failure of his speed-boosting Kinetic Energy Recovery System (KERS) in qualifying.
Despite the handicap, he still timed second quickest behind soon-to-retire team-mate Mark Webber, who will start from the front of the grid for the first time this season.
Red Bull's engineers were working overtime to fix the unidentified KERS problem, but Vettel admitted he may have to take to the circuit without it.
"We have to find the issue and solve it," said Vettel. "That's plan A. If that doesn't work we have to race without KERS."
Vettel will not be getting any favours from Webber, who was incensed by the German earlier this year when he ignored team orders and passed his stablemate to win the Malaysian Grand Prix.
"He'll do his race tomorrow and I'll do my race," said the Australian, who is looking to go out on a high in his final race at Suzuka.
"Let's see how it's looking at the end of the race. In general we'll be there for ourselves tomorrow," Webber added.
Lewis Hamilton will start third on the grid but Alonso, hoping to put Vettel's celebrations on ice, will fire up his Ferrari from eighth.
Whether Vettel clinches the championship on Sunday or not, his victory this year appears a foregone conclusion with races still to be held in India, Abu Dhabi, the United States and Brazil.
The carpenter's son from Heppenheim is set to draw level with Alain Prost with his fourth title, and will lie one off Fangio's haul of five compiled in the 1950s.
He will also be only one championship from Schumacher's five straight won with Ferrari in the 2000s. His fellow German retired for the second time last year with a record seven world titles.
Fangio was 45 when he completed his run of four consecutive championships in 1956, while Schumacher was 34 when he won the fourth of his five in a row in 2003.
Spanish officials said an autopsy showed de Villota died of natural causes. She lost her right eye and suffered severe skull damage after ploughing into a stationary truck during a test run last year.