Fernando Alonso gave Ferrari their first win on home soil for four years as the Spaniard thrust himself firmly back into world title contention with an emotional victory in the Italian Grand Prix.

Alonso has now closed the gap to 21 points on new championship leader Mark Webber who finished sixth, the Australian deposing McLaren's Lewis Hamilton after he crashed out on the opening lap.

Jenson Button, who led for the first 36 laps until ousted from top spot by Alonso in the pit stops, finished second, with Felipe Massa third in his Ferrari.

Red Bull conjured a magnificent strategy for Sebastian Vettel as he pitted at the end of the penultimate lap after having opened up a 22-second gap on fifth-placed Nico Rosberg in his Mercedes. It was enough of an advantage for him to retain fourth spot, making amends in part of his indiscretions in the last two grands prix in Hungary and Belgium.

It means with five races of an enthralling season remaining, just 24 points - a race victory these days - separate the top five.

Hamilton came to grief at the second chicane as he attempted to cut up the inside of Massa who ultimately had the line. As the Brazilian held his ground his rear-left wheel collided with Hamilton's front right, instantly breaking the suspension, sending him into the gravel and retirement - his second in the last two races.

It became apparent it was all going to come down to the one round of pit stops as to whom out of Button and Alonso would claim victory.

On lap 36 Button took the initiative and came in ahead of Alonso, followed by the Spaniard a lap later, exiting his pit box just as Button was heading down the long home straight. But as the 29-year-old returned to the track, he had his nose ahead of Button, and that was that, race over - third win of the season and 24th of his career in his pocket.

Massa finished within 4.2secs of Alonso, the top trio 24 ahead of Vettel, followed by Rosberg, then Webber who had brilliantly passed Williams' Nico Hulkenberg a few laps from the finish.

Renault's Robert Kubica, seven-times champion Michael Schumacher in his Mercedes and Rubens Barrichello for Williams completed the top 10.