MASON, Ohio Aug 17 (Reuters) - World number two Novak Djokovic has a shot at revenge against Juan Martin del Potro, who ended the Serb's medal hopes at the London Olympics, when the two clash in the Cincinnati Open semi-finals on Saturday.
Djokovic, who lost to former U.S. Open winner Del Potro in the Olympic bronze medal match less than two weeks ago, enjoyed a routine 6-3 6-2 victory over 12th seeded Croatian Marin Cilic on Friday to advance.
"It was my best match so far here in this tournament and came in the right moment, really," said Djokovic, who had an easy passage to the last eight after Russian Nikolay Davydenko retired injured during their Thursday match.
"I had the biggest challenge today with Cilic who has been playing well the last couple of months and I played a really good match."
The five-times grand slam winner may have added incentive on Saturday given Serbia's Davis Cup semi-final loss to Argentina last year in which Djokovic retired against Del Potro.
"All these losses made me stronger and, yes, they are difficult, especially when you're playing for a country and when you're in Olympic Games and we're fighting for bronze medal," said Djokovic.
"He won that match. It happens. It's a sport. You lose, you win, but the most important thing is to try to move on and become even better and even stronger from those experiences and try to win."
Del Potro overcame the surprise player of the tournament, Frenchman Jeremy Chardy, who entered the draw as a lucky loser and reached the quarter-finals thanks to wins over American Andy Roddick and Olympic champion Andy Murray.
The tall Argentine needed just 76 minutes to make sure Chardy's run stopped, surrendering only 12 points on serve and breaking Chardy four times in a 6-1 6-3 rout.
In other quarter-final action, Switzerland's Stanislas Wawrinka faces Canadian Milos Raonic, while world number one Roger Federer goes against American Mardy Fish. (Editing by Frank Pingue)