Kimi Raikkonen and Juan Pablo Montoya put the McLarens ahead of the Renaults in the final practice Saturday before qualifying for the Chinese Grand Prix, the last race of the season to decide the team title.
Raikkonen and Montoya were 1-2 in both practice sessions with the Renaults of Fernando Alonso and Giancarlo Fisichella in third and fourth places. The quartet have won 17 of the 18 races so far this season.
Raikkonen timed 1 minute, 34.253 seconds on the 5.451-kilometer (3.388-mile) Shanghai International Circuit, then bettered that with 1:33.212 in the second session.
Alonso, who clinched the drivers' title two races ago, was just tenths of a second behind the McLaren drivers in both sessions.
The McLarens will hit the track ahead of Alonso in the afternoon qualifying session for Sunday's 56-lap race.
McLaren and Renault are locked in a duel in the season-ending race which will decide the team title in Formula One this season. The order of the constructors' standings determines how much funding each team receives from the sport's governing body.
Renault leads McLaren by two points, 176-174, reversing the two-point advantage that McLaren held last week. The competition could go down to the last lap, just as Raikkonen passed Fisichella on the final circuit of last week's Japanese Grand Prix, AP reports.