The bottom 6 teams in the 2003 Constructors' Championship were entitled to run a third car in free practice on Friday.
In qualifying, Barrichello also achieved the fastest lap and secured pole position ahead of Montoya and Räikkönen.
Meanwhile, Räikkönen and Montoya engaged in an intense duel exiting the pit lane, with the Colombian getting the better of his rival.
After tire changes, Alonso led ahead of Montoya, Räikkönen, Ralf Schumacher, Sato, Barrichello, Villeneuve and Coulthard.
At the head of the race, Räikkönen followed Montoya closely, but the Williams driver managed to control him without any particular problems.
The second series of pit stops brings no changes in position between these four drivers, but allows Alonso to move up to third place, ahead of Ralf Schumacher.
Räikkönen, leading the race, pushed hard to try to overtake his rival, but when the Finn also made his pit stop, on lap 55, he returned to the track just one second behind Montoya.