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Warm-up
The drivers participated in a 30-minute warm-up session for teams to adjust their cars and setups and experiment with different levels of fuel before determining their strategies at 09:30 local time. It took place in sunny and windy weather conditions. The first nine drivers set a lap within eight-tenths of a second of Michael Schumacher's time, indicating a competitive field. forecasts predicted no rainfall throughout the race. During the race's buildup on a flat-bed truck at the pre-race drivers' parade and on the starting grid, Michael Schumacher attempted to organise a pact with the drivers that would see no overtaking at the first two chicanes. The plan failed, with Villeneuve, Benetton team principal Flavio Briatore and Arrows owner Tom Walkinshaw refusing to accept the pact; Briatore threatened to sack both of his team's drivers if they complied with the pact. and multi-car accidents at the beginning of both the Porsche Supercup and International Formula 3000 support races. He got past on the inside into the Curve di Lesmo after Ralf pushed him onto the grass into the turn. Further back, Trulli was hit by Button, who drove too fast on the slippery outside line going into the chicane, braked too late, and was sent into a spin and became the first retirement of the race.
Barrichello and Michael Schumacher started to maintain the gap between themselves and Montoya, and started to pull away from Ralf Schumacher. Irvine lost a further three positions to Häkkinen, Panis and Frentzen one lap later. Coulthard became the third retirement of the Grand Prix after an engine failure on lap seven, which meant Verstappen inherited fifth and Räikkönen moved into sixth. and was slow exiting the Variante della Roggia chicane because he out-braked himself into the turn, which allowed Barrichello to take the lead on the entry to the second Lesmo corner on the ninth lap. Barrichello began to pull away from Montoya. Verstappen fell to seventh after he was passed by Alesi and Räikkönen on lap 16. at the back of the field lost control of his car at Curva di Lesmo corner but continued driving; Barrichello (on a lighter fuel load) was able to quickly extend his lead over Montoya to ten seconds by his first pit stop on lap 19. However, Barrichello's pit stop proved problematic: his refuelling rig failed to work after it had been re-programmed and Ferrari mechanics switched to his teammate's refuelling rig, keeping Barrichello stationary for around six to seven seconds longer than planned. Barrichello exited the pit lane in third, ahead of teammate Michael Schumacher. Villeneuve made a pit stop from sixth on lap 34 and retained the position.
Barrichello closed the gap between himself and Montoya but was unable to catch up to the Williams driver who crossed the finish line first on lap 53 to clinch his maiden Formula One victory and the first for a Colombian driver. in a time of 1'16:58.393 at an average speed of .
After the race
Out of respect for those who died in the September 11 attacks, no champagne was sprayed on the podium. He also said that he was not frustrated on not claiming his first victory in the preceding 14 races as he was not expecting to win during the season. Villeneuve said to British television station ITV that he felt discussing a no overtaking pact at the race circuit was not the appropriate place: "We are race car drivers, Because we signed contracts before the season and everyone was happy to be a race car driver and to earn millions of dollars. Because we knew a year ago that there would be a race at Monza and nobody complained."
Brawn insisted the reason Ferrari opted for a two-stop strategy was to defeat Williams tactically on the high-speed circuit, adding: "We'd been trounced at Hockenheim, and I didn't really see the point in following a couple of ultra-quick BMWs down the straight." Jean Todt, Ferrari team principal, admitted that the refuelling rig issue at Barrichello's first pit stop possibly lost the driver the opportunity to win the race. Button said that he was sorry to have collided with Trulli on the race's opening lap.
The result allowed Michael Schumacher to extend his lead in the World Drivers' Championship to 50 championship points over Coulthard. Barrichello's second-place finish allowed him to narrow the gap to Coulthard to be three championship points behind. Ralf Schumacher remained in fourth position, while Montoya's victory promoted him to fifth.
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;Notes:
- – Nick Heidfeld and Giancarlo Fisichella started the race from the pitlane.
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;Constructors' Championship standings
{|class="wikitable" style="font-size: 85%;"
|-
! scope="col" |
! scope="col" |
! scope="col" | Constructor
! scope="col" | Points
|-
|align="left"| 10px
| align="center" | 1
| Ferrari*
| 161
|-
|align="left"| 10px
| align="center" | 2
| McLaren-Mercedes
| 81
|-
|align="left"| 10px
| align="center" | 3
| Williams-BMW
| 73
|-
|align="left"| 10px
| align="center" | 4
| Sauber-Petronas
| 20
|-
|align="left"| 10px
| align="center" | 5
| BAR-Honda
| 17
|-
!colspan=4|Sources: