Mercedes driver Nico Rosberg has cited three reasons for why team-mate Lewis Hamilton has pulled clear in the championship this season.
Rosberg and Hamilton fought for the 2014 title until the last race, in which the Briton was victorious, but this year Hamilton has the opportunity to wrap up the 2015 crown at this weekend's United States Grand Prix.
"I think it comes down to three things," Rosberg said when asked why Hamilton's title chance has come earlier.
"Number one is the qualifying - this has changed around this season and is definitely helping him.
"Number two is that he had a more consistent year. And number three is that I have, for whatever reason, been unluckier as well.
"So these are the three things that in my opinion came together this year and gave him that advantage."
Rosberg also reckons Mercedes' prospects in Austin have been aided by Ferrari opting to take a 10 place grid penalty due to an engine change.
"For sure it will make things a little bit easier - not only for me, but for the entire team," he said.
"To be frank, I have never thought of ending up only third in the championship, as I have a car that allows me to fight for the title win.
"So this is what I am aiming for. I know that this will be tough to realise, as I am also realistic, and I might also need quite a bit of luck, but until it is clear that there is no chance anymore, I will go for first."