Wolff: Hamilton on a level I haven't seen before

AUSTIN -- Mercedes boss Toto Wolff says Lewis Hamilton is operating on a higher level than ever before after taking five wins in the last six races.

Hamilton is now just nine points away from his fourth drivers' title after securing a decisive swing in points over championship rival Sebastian Vettel at the last four rounds. By way of direct comparison, he has outscored his Mercedes teammate Valtteri Bottas by 68 points since the summer break and Wolff says he has never seen his driver as competitive as he is now.

"I've worked with him for five years and I've never seen him operate on that level," he said. "The raw pace is spectacular, understanding the tires and the ability of the car -- which was difficult at times -- is not easy. The sustainable performance is on a level I haven't seen before."

Wolff believes a meeting to clear the air after the final round of last year's title battle with Nico Rosberg was key to Hamilton's form this season. Hamilton's four years as Rosberg's teammate were tense and the partnership ended in unusual circumstances as he backed his Rosberg into rival cars in an attempt to disadvantage his teammate. Wolff said he discussed that issue and others one evening over the winter break and believes it helped Hamilton attack this season with a fresh state of mind.

"It's my personal view, we had a difficult moment in Abu Dhabi last year and we came back together a couple of days together and had a long evening in my kitchen and took it all out. All the frustrations and questions that have grown over the year were all dismantled. We went off and he came back with a great mindset.

"He's grown stronger through the year and you can see the relationship with Valtteri is an important factor. The spirit is great within the team and through all the difficult moments that was an essential piece of the jigsaw."