Novak Djokovic swept past Marin Cilic in straight sets to book a semi-final showdown with Juan Martin Del Potro at the Cincinnati Masters.

The second seeded Serb needed just 80 minutes to beat his Croatian rival 6-3 6-2, improving his career record against Cilic to 7-0.

Djokovic, who broke Cilic a total of four times, is now on track for back-to-back titles after capturing the Rogers Cup in Toronto last week.

The world number two believes he is hitting something like top form with the US Open now just around the corner.

"It was a very good match, my best of the tournament," Djokovic said. "I'm on good form. I may have grown up on clay, but I've achieved my best career success on hardcourts."

His forthcoming clash with Del Potro offers Djokovic the chance to exact quick revenge for his defeat at the hands of the Argentine in the bronze medal match at the Olympics.

However, he insists that will not be his motivation, adding: "The match with Del Potro won't be for revenge. This is sport. You win and you lose. He is playing with confidence and it will be a big challenge to play him."

Del Potro on song

Del Potro advanced to the last four as he cruised past Andy Murray's conqueror Jeremy Chardy for the loss of just four games.

Lucky loser Chardy had taken full advantage of his chance in draw as he dumped Murray out on Thursday evening, but he found Del Potro in far less forgiving mood as the South American romped to a 6-1 6-3 success.

Del Potro - who shrugged off fears over a wrist injury - was in complete control from the off and broke twice in each set on his way to victory in just 76 minutes, surrendering only 12 points on his own serve.

"I broke his serve very early, so that has given me confidence to still play, be healthy and relax and don't think about my wrist," Del Potro said.

"I'm in good level at the moment after the Olympics. I get confidence to play against all the players."