Lewis Hamilton has backtracked on his own admission that the World Championship is over after Sebastian Vettel claimed victory at the Italian Grand Prix, but admits it will be a tough task to catch the German.

The Red Bull driver extended his lead at the summit of the championship to 53 points over Ferrari's Fernando Alonso with his sixth victory of the year at Monza while Hamilton, now 81 points adrift, struggled to an unimpressive ninth, announcing: "That's it for the Championship" as he stepped out of his car.

But after coming to terms with a frustrating weekend which included a slow puncture and his worst qualifying performance in three years, the Mercedes driver was in more optimistic mood by Sunday evening.

"When I got out of the car I was angry and definitely thought that could be it," Hamilton told Sky Sports. "But I went back to my engineers... and I'm not going to give up.

"I was a difficult weekend. I'm ninth, and we should have been much further ahead. So I am very disappointed with myself.

"I blew it in qualifying and it was impossible to catch up," he added.

"The radio failed in the race and I didn't know what the hell was going on. I missed my pit stop by quite a few laps. It was a disaster of a weekend.

"I've got to win every race basically. It's the tallest order ever, but I can do nothing but try. Our car was good in Hungary when we had higher downforce and we'll have that going into Singapore when we can hope for some improvements.

"I hope we'll be strong, get some more wins this year. I wish it was a closer battle at the front. It's a shame it is like this."

Vettel's dominant performance denied Ferrari a home victory as Alonso finished second with Mark Webber in third as Red Bull's grip on the contructors' title tightened with seven races remaining.