Final race positions after 62 laps:
1 F Alonso (Renault)
2 M Schumacher (Ferrari)
3 J Button (BAR)
4 A Wurz (McLaren)
5 T Sato (BAR)
6 J Villeneuve (Sauber)
7 J Trulli (Toyota)
8 R Schumacher (Toyota)
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Lap 62: Alonso's brilliant drive is complete as he keeps Michael Schumacher's Ferrari at bay on the final lap to get home by 0.2 seconds and win his third race in a row.
It makes it four wins out of four for Renault this season, but Schumacher's amazing charge from 13th place on the grid has signalled that he and Ferrari are well and truly back to form.
Lap 61: Schumacher is all over Alonso's gearbox, but again the Spaniard holds firm and the world champion locks up a brake on his Ferrari.
Lap 60: Alonso is still hanging on at the front. With just two laps to go, can Michael Schumacher do anything to get past?
Lap 58: It looks like it will take a mistake from Alonso now to deny him a third straight win, but Michael Schumacher is right there to pick up the pieces if he slips up.
Lap 56: Backmarkers are starting to come into view now as Michael Schumacher stalks leader Alonso.
Lap 55: Michael Schumacher's Ferrari is all over the back of Alonso's Renault, but the laps are continuing to tick away.
Lap 54: There is an anxious moment for the Renault team as Michael Schumacher pulls out to attempt a pass, but Alonso shuts the door.
Lap 53: Michael Schumacher continues to test leader Alonso's title credentials, but he has not yet got his Ferrari close enough to attempt a pass.
Lap 51: It is now down to whether Alonso can hold off Michael Schumacher's Ferrari, which is clearly the quicker car.
BAR's Button looks set to have to settle for third.
Lap 50: The pressure is all on championship leader Alonso as the Renault driver has Schumacher's Ferrari looming large in his mirrors.
Lap 49: Schumacher finally comes in for a pitstop at the end of the lap and he does not manage to get his Ferrari out in front of Alonso, who regains the lead.
Lap 48: Button pits from second place as Schumacher puts in another fastest lap to crank up the pressure on Alonso.
Lap 47: Michael Schumacher takes advantage of a scrap between the two Williams, who are about to be lapped, to get past Button and take the lead.
The Ferrari driver's victory chances are now very much alive, even though he still has to make his second pitstop.
Lap 45: Michael Schumacher does not look like being able to get past current leader Button, and a pitstop looks imminent.
Alonso, who is in third and has already pitted, is looking good.
Lap 43: Michael Schumacher is now so close to Button that he is being held up, which could play into Alonso's hands when the second round of pitstops is over.
Lap 42: Alonso makes an early pitstop from the lead.
His victory chances look under serious threat from the fast-closing Michael Schumacher, who looks set to stay out several more laps.
Lap 41: Michael Schumacher has taken another second out of the leading pair.
Lap 40: With the second round of pitstops looming, Michael Schumacher is less than three seconds behind Button in second, and within 12 seconds of leader Alonso.
Lap 38: Things are really hotting up now as Michael Schumacher's Ferrari closes the gap on second-placed Button to just over five seconds.
Button, meanwhile, has gained almost a second on leader Alonso.
Lap 37: Massa barges his Sauber past Coulthard's Red Bull to take 12th place.
Lap 36: Leader Alonso has kept his advantage over Button's BAR above 10 seconds, but his advantage over Michael Schumacher in third is now down to 18 seconds.
Lap 34: At this rate, Michael Schumacher's Ferrari will be in a position to challenge Button's second place within the next eight laps.
Lap 33: Michael Schumacher has cut the gap to second-placed Button's BAR to just 13 seconds as he continues his charge.
Lap 31: Ferrari's Michael Schumacher is going so well that he could end up seriously troubling leading pair Alonso and Button if he can keep up the same pace.
Lap 30: Mark Webber pays for a mistake in the Williams as Jacques Villeneuve passes him to snatch seventh place.
Lap 29: Button suddenly has something to worry about in second as Michael Schumacher's lightning-quick Ferrari starts reeling him in.
Lap 28: Alonso's advantage at the front is back at the 10-second mark. Michael Schumacher is third, 31.6 seconds behind the leader.
Lap 27: Alonso has managed to extend his lead over second-placed Button after the first round of pitstops.
Michael Schumacher's long run has enabled him to move up from 12th to third, while Wurz is up to fourth in the McLaren.
Lap 26: Michael Schumacher is reaping the benefit of being able to stay out for a few extra laps as he sets another fastest lap.
Lap 25: As a string of drivers come in for pit stops, Michael Schumacher takes advantage to record the fastest lap of the race so far.
The world champion looks set to jump right up the order when he eventually makes his pitstop.
Lap 24: Button gets a lap to try and eat into Alonso's lead as the Renault driver comes into the pits.
Lap 23: Trulli and Webber pit together but the Toyota driver gets out still in front of Webber's Williams.
Lap 22: Sato puts a move on Mark Webber to snatch fourth place from the Williams driver.
Lap 21: Button continues his scorching pace with another fastest lap, taking more than a second out of Alonso's lead.
Lap 20: Ferrari's nightmare start to the season takes another turn for the worse as Barrichello crawls into the pits and retires from the race.
Button continues to pressure Alonso with the fastest lap of the race so far.
Lap 19: Ferrari's Barrichello is the first driver to pit. Button, meanwhile, has reduced to gap to leader Alonso to 8.7 seconds.
Lap 18: We have yet to see a successful passing move.
Sauber's Massa tries one on Coulthard's Red Bull and has to pit after losing a piece of his front wing.
Lap 17: Michael Schumacher shows no signs of making an impression on brother Ralf and is still down in 11th place.
Lap 16: Leader Alonso starts to carve his way through the backmarkers.
Lap 14: The gap between leader Alonso's Renault and the BAR of second-placed Button is remaining relatively constant around the 10-second mark.
Lap 12: Michael Schumacher's day is not getting any better.
He has still failed to get past brother Ralf's Toyota and is almost 30 seconds adrift of leader Alonso.
Lap 11: Jenson Button is now up to second but he is still lapping slower than leader Alonso, who holds an advantage of more than eight seconds.
Third-placed Jarno Trulli looks to be holding up the cars behind him, with Webber, Sato, Wurz, Villeneuve and Barrichello all in hot pursuit.
Lap 10: The new Minardi of Patrick Friesacher becomes the third car to drop out of the race.
Lap 9: There is drama at the front as leader Raikkonen's McLaren slows down and Alonso roars through into the lead.
The Finn's car crawls to a halt and his race is over.
Lap 7: Alonso is three seconds behind Raikkonen, but the gap to Button in third is almost 10 seconds as he laps about one second slower.
Lap 6: While Alonso continues to chase leader Raikkonen, his Renault team-mate Fisichella crashes out from 11th place.
Lap 5: Ferrari's Michael Schumacher is still trying to get past his brother Ralf's Toyota as he languishes in 13th place.
Lap 3: BAR's Jenson Button is already seven seconds adrift of the leading pair as he chases from third.
Lap 2: Raikkonen increases his lead over Alonso to 2.6 seconds.
Michael Schumacher, who started 13th in the Ferrari, has yet to gain a place.
1302: Raikkonen gets away well from pole and holds his position as Alonso challenges into the first corner.
The McLaren driver holds a two-second lead after the first lap.
Trulli gains a place over Mark Webber to go into fourth, while Villeneuve gets a great start to move up to eighth.
1300: Raikkonen leads the cars away from the grid for the parade lap. Conditions are overcast, but dry.
McLaren's Kimi Raikkonen starts the San Marino Grand Prix from pole position after a stupendous lap in final qualifying on Sunday morning.
Raikkonen, who was only 0.003 seconds ahead in first qualifying, produced a combined time of two minutes 42.880secs to extend his advantage over world championship leader Fernando Alonso's Renault to 0.561secs.
The two look set to fight a private battle for victory in Imola - Jenson Button in third place was more than 0.5secs adrift in third place.
Michael Schumacher, who was third fastest after first qualifying, ran off the track on his final qualifying lap and will start 14th.
That is a massive blow to Schumacher, who needed a win in Imola to kick start his 2005 campaign.
The world champion is already 24 points behind Alonso after just three races following a disastrous start to the season by his Ferrari team.