Monza: Nico Rosberg has no intention of giving Mercedes team-mate Lewis Hamilton an easy ride to his third world title despite falling 53 points behind him in the race for this year`s championship after Sunday`s Italian Grand Prix.
The 30-year-old German, who retired with a blown engine with two laps remaining, had his worst day of the season as the defending two-time champion Briton drove to his 40th career win in commanding style.
"It`s a fact that it`s a massive step in the wrong direction," said Rosberg.
"It`s the biggest loss I`ve had in one day throughout the whole season, so that`s very bad, and I now need to catch up a few points.
"I keep going. Giving up doesn`t exist for me. So, I`ll just keep fighting and I`ve got to try to win the next couple of races somehow."
Rosberg`s problems began on Saturday morning when after final free practice a cooling system leak meant he had to change engines - and revert to an older unit used at last month`s Belgian Grand Prix.
"The whole weekend just went completely wrong and unlucky I think," he added. "There were so many repercussions of this engine issue.
"It wasn`t an engine issue, actually. It was a chassis issue that made me have to change. To have it explode two laps from the end was unbelievable. It`s even more disappointing.
"I was going to have a good go at Vettel because finally I had the brakes cool enough to attack and I could ramp up the electric power, and I was going to really go for it."
His engine failure came after a poor start, a recovery and then a team decision to give his power unit a boost in the final laps.
"We gave it a little push at the end to try to catch Sebastian and this is when it decided to call it a day," said team boss Toto Wolff.
"The engine was on its sixth race so it was very high on miles and we didn`t get any warnings."