The 24-year-old began the opening day of free practice with a $2,000 fine for speeding in the pit lane and closed it as the quickest race driver in the second session.

With fans chanting his name and banners draping the grandstands, Alonso gave the crowd only a brief glimpse of his car in the morning with just two timed installation laps.

The afternoon was a more red-blooded session, with the drivers who had been saving their engines venturing out on to the track.

Even then the top two times were set by the unsung test drivers, with Briton Anthony Davidson quickest for Honda in one minute 16.533 seconds ahead of Red Bull's Dutch reserve Robert Doornbos.

Ferrari's Brazilian Felipe Massa and seven times champion Michael Schumacher were fastest in the morning when only three of the drivers who will race on Sunday set times.

Massa, fresh from the first podium finish of his career after taking third place at the Nuerburgring last weekend, claimed the quickest lap of the day in 1:15.796.

Schumacher, winner of the last two races and 13 points adrift of Alonso in the championship after five rounds, clocked 1:16.099.

McLaren's Kimi Raikkonen, last year's winner in Barcelona, did not leave the garage in the first session and was only 15th in the second.

Alonso, winner twice this season and runner-up in the other three races, will start Sunday's grand prix with the same engine he used at the Nuerburgring.

Schumacher and Massa have fresh engines.