Monza: Lewis Hamilton conceded that his bid to win a second driver's world title was over on Sunday after he finished a distant ninth for Mercedes in the Italian Grand Prix.
The 28-year-old Briton, who had qualified 12th after a disappointing qualifying session on Saturday, was hit by more problems on Sunday as defending triple world champion German Sebastian Vettel claimed his sixth win of the year for Red Bull.
Vettel now leads third-placed Hamilton by 81 points in the title race.
Hamilton said: "It's awful when you are just empty of energy and have given everything for just two places -- and that's it for the championship now.
"It was a very difficult weekend. Ninth. I should have been much further ahead and I am very disappointed with myself. I blew it in qualifying and it was impossible to make up the places.
"Overall, it has been a nightmare, a disaster of a weekend.
"Of course, I will keep on pushing and give it my best and try to win some races and take some points here and there but in that car he is so fast."
Hamilton, who had slid off the circuit at the Parabolica and damaged his car during qualifying before being blocked by German Adrian Sutil's Force India, suffered similar ill fortune on Sunday.
He lost the use of his radio and picked up a slow puncture that forced him to switch strategy, adding a pit-stop, during the race.
He said: "It was almost like driving blind, you don't know when to pit, when to push and what is going on."
The team had to use old-fashioned pit-boards to signal instructions to him to pit for tyre changes.