MONZA, Italy (AP) — McLaren driver Lewis Hamilton won the Italian Grand Prix on Sunday, and Formula One leader Fernando Alonso of Ferrari finished third to extend his overall lead.

Hamilton put speculation about his future and a possible switch to Mercedes behind him to claim his first victory at Monza and the 20th of his career.

It's unlikely to have much impact on the championship after an impressive race from Alonso, much to the delight of the fans at Ferrari's home track. The Spaniard started from 10th on the grid after he had technical difficulties during qualifying.

Hamilton moved past defending champion Sebastian Vettel to take second place in the drivers' standings, 37 points behind Alonso.

Vettel had to retire because of a mechanical problem when wisps of white smoke started to emerge from his car with six laps to go. He was joined on the sideline by Red Bull teammate Mark Webber, who retired at the end of the penultimate lap.

Jenson Button was forced out of the race on the 35th lap just when the McLaren driver was looking on course for second place.

Sergio Perez was second on Sunday, 4.3 seconds behind Hamilton after starting 12th. The Mexican finished strongly, moving through the field in the closing stages and cutting into Hamilton's lead.

Ferrari driver Felipe Massa finished fourth after starting third. The Brazilian got off to a strong start, overtaking Button and almost moving past Hamilton on the outside just before the first chicane.

Alonso made up three places on the first lap from 10th, and was up to sixth by the second lap.

A tremendous tussle with Vettel halfway through the race forced Alonso onto the grass adjacent to the track to avoid a collision, with the German later being issued a drive-through penalty.