Jenson Button has claimed that Lewis Hamilton needs a greater challenge in Formula 1 than his rivalry with Mercedes teammate Nico Rosberg.

Hamilton could win his third F1 title with victory in the US Grand Prix, scheduled for Sunday in Austin, after winning nine races out of 15 so far this season.

However, Button insists that the challenge of Rosberg, who sits 73 points behind his fellow Mercedes driver in third in the standings, is not enough for the 30-year-old and that he needs the challenge of another team to spur him on to greater things.

"Lewis has had an easy ride this year," Button told The Guardian. "That has definitely helped, he has definitely learned along the way.

"I am sure that Lewis would like, as all of us would, another team to fight against. It is much more fun fighting another team.

"Mercedes are such a big team that no one can catch them. That is the biggest issue facing Formula 1. Hopefully there will be more competition next season and then it will be more satisfying to win a world championship."

Hamilton finished fastest in the final practice session ahead of this weekend's race before qualifying was postponed due to heavy rain.