In what pass for cool conditions at Sepang with the trackside temperature a modest 36 degrees Celsius (96.80F), many top drivers preferred to sit out most if not all of the session to preserve their engines, which will be running for a second race on Sunday.

Portuguese Tiago Monteiro had the worst possible start to his weekend when his Midland ground to a halt on the trackside grass 40 minutes into the session.

Wurz drove his Williams around the 5.5km circuit in one minute 34.946 seconds, 0.787 seconds faster than BMW's [ Images ] Robert Kubica [ Images ] and more than a second faster than Honda's Anthony Davidson [ Images ].

Wurz's pace will be another boost for Williams after their surprise success at having both race drivers score points in the season-opening race in Bahrain last week.

TOP TRIO

None of Friday's top trio will race on Sunday and of those who will be on the grid, McLaren's [ Images ] Colombian driver Juan Pablo Montoya [ Images ] was quickest with a lap of 1:36.709 for fourth place on the time charts.

Among the four cars starting with new engines this weekend -- and losing 10 places on the grid as a result -- will be Ferrari's [ Images ] Felipe Massa [ Images ].

The Brazilian put in the most laps (18) of the top race drivers and managed the seventh fastest time, while his team mate Michael Schumacher [ Images ] recorded the sixth fastest time on one of his four laps.

World champion Fernando Alonso [ Images ] and his Renault [ Images ] team mate Giancarlo Fisichella [ Images ] remained in the garage for the first of Friday's two practice sessions.