Lewis Hamilton battled back from a troubled start to win the Italian Grand Prix after Mercedes team mate Nico Rosberg cracked under pressure and saw his Formula One championship lead cut to 22 points.
Rosberg, whose 29th lap mistake at the first chicane cost him the lead and the race, finished second as dominant Mercedes celebrated a first one-two since Austria in June and their seventh in 13 races.
Brazilian Felipe Massa was third for Williams in his first podium appearance since May 2013.
Rosberg, who now has 238 points to Hamilton's 216 with six races remaining after the end of the European part of the season, recognised his error.
"It's a terrible feeling to lose the lead like that but in the end Lewis was really quick in the whole race. He came like a rocket and I had to push and I made the mistake," he said.
With the sport taking a deep breath as the rivals lined up together on the front row, two weeks after they had collided in Belgium on the second lap, the start provided immediate drama.
Hamilton had taken pole position for the first time since May but problems with the car's start controls left him struggling to get away. He was fourth into the first corner as Rosberg led untroubled but kept his cool.
"I'm quite grateful today that I didn't lose it, I didn't end up crashing in the first corner, I didn't end up touching anyone, I didn't end up locking or anything like that. I managed to keep my composure," he said.
It was the start of a thrilling chase, with the 2008 world champion hunting down his quarry and seizing the lead when Rosberg missed the chicane.
The Briton had earlier shunned advice from his race engineer to back off and save tyres for a later attack and it proved the right approach.
The two crossed the finish line 3.1 seconds apart, with Hamilton celebrating his first win since Britain in July. It was his sixth of the season and 28th of his career, taking him ahead of triple champion Jackie Stewart in the all-time lists.
DIFFICULT RACE
"It was a difficult race," said Hamilton. "For whatever reason, at the start the button didn't press which engages the launch sequence.
"For the formation lap it didn't work and when I got to the grid and put it on again, again it didn't work. It was very strange. I've never really had that happen before."
In a sport full of conspiracy theorists, Rosberg and team bosses ridiculed a suggestion that he might have been ordered to cede place to Hamilton as a result of what happened in Spa.
"I've heard about that, but what would be the reason for me to do something like that deliberately? There is no possible reason," he said, explaining that he had missed the chicane to avoid locking up and 'flat-spotting' a tyre - which would have forced an extra pitstop and a lot of lost time.
Massa's podium came on Brazilian independence day and after the team had announced the former Ferrari driver was staying for 2015 along with Valtteri Bottas.
The points, at the fastest track on the calendar, meant Williams leapfrogged Ferrari into third place.
"I hope really we can get this third place in the Constructors' Championship. It would be fantastic for the whole team. I'm so happy to be on the podium here in this amazing place that I really love," said Massa.
In the absence of their current Ferrari heroes, the passionate home crowd welcomed Massa onto the podium with cheers as they spilled out in a vast red wave onto the finish straight.
Rosberg, blamed by his own team for the second lap Spa collision that led to Hamilton's retirement from that race, was booed for the second grand prix in a row.
Massa's Finnish team mate Bottas was fourth following another impressive day of overtaking after he had dropped from the second row to 10th at the end of the first lap.
Ferrari's Fernando Alonso retired from his team's home race on lap 29 with a failure in the car's energy recovery system, his first mechanical retirement in 86 races, while Kimi Raikkonen finished ninth.
The Finn crossed the line 10th but moved up after McLaren's Kevin Magnussen was penalised for forcing Bottas off.
Until Sunday, Alonso was the only driver to have scored points in every race this season.
Australian Daniel Ricciardo, winner of the two previous races, had another brilliant race for Red Bull and finished fifth after some breathtaking overtaking moves including one on four times champion team mate Sebastian Vettel who was sixth.
Mexican Sergio Perez came seventh for Force India after a wheel-to-wheel battle with McLaren's Jenson Button in eighth. The championship now heads east to Singapore and Japan. (Reporting by Alan Baldwin, editing by Pritha Sarkar and Justin Palmer)
