* Lap 1: Pole-sitter Juan Pablo Montoya makes a clean start to beat world championship leader Fernando Alonso into the first turn. Jenson Button grabs third from Jarno Trulli and Takuma Sato, but the Japanese driver hits back on the approach to Parabolica. Rubens Barrichello gets ahead of team-mate Michael Schumacher to lie sixth. Giancarlo Fisichella is eighth from Ralf Schumacher, Jacques Villeneuve, Kimi Räikkönen (fastest in qualifying, but docked 10 places because of an unscheduled engine change), Felipe Massa, Christian Klien, Antonio Pizzonia (in his first start since Monza after being drafted in to replace the unfit Nick Heidfeld), Tiago Monteiro and Robert Doornbos. David Coulthard and Mark Webber pit after sustaining minor damage in the first-corner jam. Christijan Albers and Narain Karthikeyan come in, too, after colliding at the first corner. All rejoin. Montoya leads by 1.5s at the end of the lap.
* Lap 2: Both Ferraris pass Trulli. Montoya leads by 2.1s.
* Lap 3: Montoya pulls away again – 2.4s. The top two are edging away from Button. There’s a minor queue developing behind Sato. Räikkönen is still bottled behind Villeneuve.
* Lap 4: Trulli repasses Michael Schumacher for sixth.
* Lap 7: Alonso bags fastest lap so far: 1m22.685s. He trails by 2.2s.
* Lap 10: The top two are 14s clear of third-placed Button.
* Lap 11: Monteiro makes the first scheduled stop.
* Lap 12: Alonso laps in 1m22.376s and cuts his arrears to 1.9s.
* Lap 13: Michael Schumacher pits.
* Lap 14: Barrichello and Villeneuve come in: Räikkönen is unshackled. Talking of which, Montoya laps in 1m21.988s.
* Lap 16: Sato and Doornbos pit.
* Lap 17: Button pits on schedule, Sato returns after a refuelling glitch.
* Lap 18: Klien peels in.
* Lap 19: Alonso and Massa refuel.
* Lap 20: Montoya and Trulli pit.
* Lap 21: Fisichella comes in. Coulthard and Webber are having a ferocious tussle – albeit for 15th place. Räikkönen passes the fuel-heavy Alonso for fourth.
* Lap 22: Ralf Schumacher pits.
* Lap 23: Pizzonia pits. Räikkönen – now second on the road, pending his stop – laps in 1m21.725s…
* Lap 24: …and 1m21.629s.
* Lap 25: Räikkönen finally pits. He rejoins fifth.
* Lap 26: Montoya leads Alonso by 9.5s. Webber pits.
* Lap 28: Räikkönen suffers a cut left rear tyre. He pits for a replacement and slips to 11th. Coulthard refuels – and rejoins behind Webber.
* Lap 29: With everybody having pitted, Montoya leads Alonso, Fisichella, Trulli, Button, Ralf Schumacher, Barrichello, Michael Schumacher, Pizzonia, Massa, Villeneuve, Räikkönen, Klien, Sato, Webber, Coulthard, Monteiro, Doornbos, Albers and Karthikeyan. Albers is given a drive-through penalty for failing to heed blue flags.
* Lap 31: Monteiro pits.
* Lap 35: Button pits.
* Lap 36: Michael Schumacher comes in.
* Lap 37: Barrichello pits.
* Lap 39: Alonso and Villeneuve pit.
* Lap 40: Montoya, Fisichella and Trulli pit.
* Lap 41: Ralf Schumacher and Massa refuel.
* Lap 43: Barrichello – again – Klien, Sato and Webber pit. The Ferrari driver replaces his left-rear tyre.
* Lap 45: Räikkönen spins down from fourth to fifth at the Variante della Roggio.
* Lap 47: Räikkönen repasses Trulli for fourth at the Parabolica.
* Lap 49: Montoya slows noticeably – his left rear appears to be blistered. He carries on but reduces his pace. Alonso closes in.
* Lap 50: Having harried Button since the second fuel stops, Michael Schumacher runs off at the second Lesmo and slips to 10th.
* Lap 51: Räikkönen laps in 1m21.504s.
* Lap 52: Alonso is within 3.5s of Montoya.
* Lap 53: Montoya wins by 2.4s from Alonso. Fisichella, Räikkönen, Trulli, Ralf Schumacher, Pizzonia, Button, Massa and Michael Schumacher. Villeneuve, Barrichello, Klien, Webber, Coulthard, Sato, Monteiro, Doornbos, Albers and Karthikeyan are all lapped. All 20 starters are still running at the end.