US Open champion Marin Cilic made a shock first-round exit from the Shanghai Masters yesterday after losing 7-5 2-6 7-6 to fellow Croatian Ivo Karlovic.

After dropping the first set, Cilic broke his opponent twice in the second to force a decider but Karlovic clinched the tie-breaker to seal victory in two hours and 16 minutes.

Cilic, sixth in the race to November’s elite eight-player ATP Finals in London, had won his last two matches against Karlovic, who blasted 20 aces to his opponent’s nine.

It proved a good day for big-servers as world no.14 John Isner belted down 22 aces to beat Pablo Andujar 7-6 1-6 6-3.

The American, who lost to Tomas Berdych in the China Open quarter-final last week, won 71 per cent of his service points to win in just over two hours.

“Beijing was great last week,” said Isner.

“I had a pretty good tournament. Got my tail kicked in the quarters. But I’m playing pretty well.”

Juan Monaco downed Joao Sousa 6-2 7-6 to set up a second-round clash with eighth seed Milos Raonic.

Novak Djokovic, Rafa Nadal and Roger Federer are together this week in Shanghai for the first time since Wimbledon having already secured their places at the London season finale.

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