Spain’s Tommy Robredo toppled world number one Novak Djokovic 7-6 (8-6) 7-5 on Thursday to reach the quarter-finals of the Cincinnati Masters.

It’s the second straight week that Wimbledon champion Djokovic has slumped to defeat in the third round of an elite Masters level event, after an exit at the same stage in Toronto.

The Serb will now have to regroup before the final Grand Slam of the year, the US Open which starts August 25 in Flushing Meadows.

Earlier, Andy Murray battled more than two hours against the huge serve of John Isner, finally dispatching the American 6-7 (3-7) 6-4 7-6 (7-2) to reach the quarter-finals.

Two-time champion Murray saved a pair of match points in the 12th game of the third set as Isner hit the net with errors.

The American, runner-up to Rafael Nadal in Cincinnati last year, was then caught by a passing shot before Murray levelled at 6-6 with an ace.

The Scot bore down in the decisive tiebreaker, ending the match with his 14th ace.

Murray, in search of his first title since Wimbledon in 2013, has struggled to regain top form since his return from back surgery in January.

He next faces either second-seeded Roger Federer or Gael Monfils as he tries to add a third Cincinnati title to those he won in 2008 and 2011.

Australian Open champion Stan Wawrinka, the third seed, rallied to beat Croatian Marin Cilic 3-6 6-0 6-1 while Italian 15th seed Fabio Fognini recovered to eliminate Lu Yen-Hsun of Taiwan 3-6 6-3 6-3.

Frenchman Julien Benneteau advanced into the last eight with a 7-5 6-1 win over Poland’s Jerzy Janowicz.

The combined ATP Masters and WTA hardcourt event is the last major tune up for the US Open, the final Grand Slam of the year that starts at Flushing Meadows on August 25.