Novak Djokovic had a comfortable first match at the Shanghai Masters, dispatching Grigor Dmitrov 6-3, 6-2 to enter the third round.

Djokovic did not face a single break point the whole game, with his 21-year-old opponent not able to garner more than one point in any of the Serbian's service games.

"Very pleased with my serving in Beijing and obviously the first match today," said Djokovic, who will face Feliciano Lopez in the third round. "So that's something that I've been working on, obviously.

"Relying on the serve in today's tennis is a big advantage. So I try to get as many free points as possible. Today that was the case. It helped me a lot to defeat my opponent."

The Serbian also admitted the tennis circuit was missing Rafael Nadal, who has not competed in a single tournament since his second round exit at Wimbledon.

"There is definitely a difference when he's around and when he's not around," the world number two said. "I don't think there's a big difference, a significant one which would maybe affect in a negative way tournaments where we are playing.

"But there is still, you know, a big group of people that follows him, support him. He's definitely one of the best tennis players ever to play the game and an extremely popular global, successful athlete, recognized all over the world. So there is a certain excitement when he's around, that's for sure."

Asked if tennis would be able to cope once Federer and Nadal, two of the game's greatest ever players, retire, Djokovic said: "Federer and Nadal are two very popular athletes. As I said, both of them, maybe two out of four best players ever to play this game. So to be able to compete with them, it is something special.

"But I know as somebody, when I was starting to play professional tennis tournaments, got to No. 3 of the world, I know how much struggle I had to go through mentally. Obviously with confidence and self‑belief, you know, after I lost many of the important matches against those guys. But they made me also work harder. They made me believe more in myself, be more professional, more dedicated.

"It is great to be part of their era. It is what it is. But as expected in a course of life you get a new generation that is coming up. Andy won his first Grand Slam this year. But he always was one of the best players in the world in the last four years. We have Del Potro. We have some newcomers like Raonic, Berdych is always there, and Tomic.

"We'll see. I believe that tennis will stay the way it is because we're experiencing some really good times. I'm sure that more players will join that top group."