Ferrari felt the pain on Sunday after emerging with just two points from a hard day in front of their home fans at the Italian Grand Prix.
Deliberate? I just made a mistake, says Rosberg
Hamilton wins in Italy to rein in Rosberg
Fernando Alonso had started the day as the only driver to score in every race this season but his involvement ended after 29 laps when he pulled over and parked up with a problem with the car's energy recovery system.
It was the first time in 86 races, since the 2010 Malaysian Grand Prix, that the Spaniard had been halted by a mechanical failure.
His last race retirement was in Malaysia in March last year when he collided with Mark Webber and ended up in the gravel.
Team mate Kimi Raikkonen had crossed the line 10th but moved up to ninth place after McLaren's Danish rookie Kevin Magnussen was penalised for forcing the Williams of Valtteri Bottas off the track.
The meagre haul, coupled with third and fourth places for Williams with former Ferrari driver Felipe Massa back on the podium in third place, saw Ferrari slip to fourth in the constructors' standings behind Williams.
"In Formula One, as in sport in general, there are days to forget and this was certainly one of them," said team principal Marco Mattiacci.
"Unfortunately, we had no way of predicting the problem that affected Fernando's car, but I am sorry that it happened right here in Monza at our home race."
Ferrari had always known Spa and Monza, two high-speed low-downforce tracks, would be difficult for the characteristics of their car with Alonso qualifying only seventh and Raikkonen starting 11th.
The fans still made their allegiances clear, with the main grandstand on the pit straight festooned with banners and messages of support.
Rosberg error hands Hamilton victory
Lewis Hamilton battled back from a troubled start to win the Italian Grand Prix on Sunday 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 tensions soaring, either Hamilton or Rosberg could leave Mercedes'
McLaren boss Ron Dennis has said that the tensions between Formula One title rivals Lewis Hamilton and Nico Rosberg could result in one of them leaving Mercedes at the end of this season.
McLaren's chairman, who says his team is some way from finalising their own driver line-up, has experienced similar battles between teammates in the past. He said that no one could have predicted the tension within Mercedes Benz.
Dennis said that McLaren can imagine a range of scenarios that could see one of their drivers on the market by the end of the year, The BBC reported.
Hamilton and current championship leader Rosberg collided at the Belgian GP two weeks ago and have since been warned by Mercedes boss Toto Wolff that the team would have to consider changing their driver line-up if they are not able to manage the two of them following the Mercedes racing spirit.
Rosberg has recently extended his contract for a further two years, with an option for more, while Hamilton has another year on his to run and is keen to extend it.
Dennis said that if Hamilton or Rosberg were to become available that does not mean McLaren would automatically reach for that driver, or any other driver, in preference to what they already have.
Both Mercedes drivers are under contract for 2015. Hamilton''s deal runs out at the end of next season, and Rosberg has extended his until at least the end of 2016, the report added.
