ATP Finals: Djokovic Separated Himself From Federer, Nadal, Greg Rusedski Says

Novak Djokovic has separated himself from the likes of Roger Federer, Rafael Nadal and the rest of the pack, according to former coach Greg Rusedski.

Djokovic got his ATP World Tour Finals off to a winning start with a comfortable 6-4, 6-3 win over American John Isner at the O2 Arena in London on Monday night.

“The O2 Arena has been a lucky place for me over the years," Djokovic said, as quoted on The Express. "I’ve had plenty of success. The match was great. I managed to have three breaks of serve against John which is sometimes mission impossible but I just managed to be there at the right time."

“I held my serve really well and backed it up from the baseline very solid. Just a great match overall," he added.

The win was the Serbian's 32nd in his last 34 games in the second half of 2018 that has seen him emerge victorious at Wimbledon, the Cincinnati Masters, the US Open and the Shanghai Masters.

Djokovic is already guaranteed to end the year atop the rankings and could further strengthen his lead at the top with victory in London. And after the way he started the calendar year with inconsistent results, he is now on a different level, according to Rusedski.

“Djokovic is just too good,” Rusedski explained. “He has separated himself from the pack. You have the world No. 1 and then there's the rest."

“That's hard to believe considering where Djokovic started the year at. He was in the wilderness and the way he played tonight, it was as good as it gets,” he said.

Meanwhile, Isner was full of praise for Djokovic, in particular, his return game.

The North Carolina native is known for his potent serve as he approaches 11,000 career aces, but it was nullified by the 31-year-old, who he considers the best returner he's ever faced.

"He's the best returner I've ever faced for sure," Isner said after the match. "I've said that before, too. So he's a very good tennis player. He is [the] No. 1 and No. 2 and No. 3 [best returner in the world]."

"From the first point of the whole match he connected pretty well on a return. But I mean, to be honest, I'm not surprised. Sometimes you got to hope he's a bit off. Unfortunately, I don't think that was the case tonight. I got my a-s kicked. That was pretty comprehensive out there," he said.

Djokovic is the leader in his group along with Alexander Zverev and will face the young German on Tuesday in a match that will likely determine who goes through to the semifinals. Zverev defeated Marin Cilic 7-6, 7-6 earlier.

On the other side, Kei Nishikori and Kevin Anderson currently lead their group after their respective wins over Federer and Dominic Thiem. Federer will look to get back to winning ways against Thiem, who he will face for the first time since 2016 on Tuesday.