Mercedes technical boss Paddy Lowe says Nico Rosberg's main area of improvement this year has been his racecraft.
After being beaten to the title by Lewis Hamilton in 2014 and 2015, Rosberg only needs to finish second to his teammate at the four remaining races of the season to secure the drivers' championship this year. While Hamilton has suffered more mechanical failures than Rosberg this year, the German has capitalised on his rival's misfortune by securing nine wins in 17 races.
After observing Rosberg at the team for the last three years, Lowe believes the key to the German's improvement this season has been the way he races against other drivers.
"I think Nico is an incredibly strong driver and I think we have seen over the last three years that he can qualify extremely well," he said. "I think, for me, the step that he has made this year is that he has improved his racecraft considerably."
Rosberg has incurred three high-profile penalties for his driving this year, one for colliding with Hamilton in Austria, one for running Max Verstappen off the road in Germany and one for barging past Kimi Raikkonen in Malayisa (pictured). But despite the stewards taking a dim view of Rosberg's driving this year, Lowe insists the overall change has been positive.
"He's proving himself much better able to fight for the positions. He's come across a few points along the way, with a few incidents that didn't quite come off how he wanted, but overall that's where he has made the step."
Lowe says one of Rosberg's biggest problems is having to go up against a driver as good as Hamilton.
"Lewis gets better every year," Lowe said. "He is a very, very difficult guy to beat for Nico, so in one way that's unfortunate for Nico to have such a strong teammate, but the two together are an incredible force for the team -- they push each other.
"That's what is fantastic. When you have two very strong team-mates is that they actually elevate the total performance of the team, and we see that. We have races such as Monza where Lewis was incredibly strong and then Singapore where Nico was incredibly strong and that's what you need, for each driver to push each other to new limits."