Andy Murray crashes out to Jeremy Chardy in Cincinnati Open

World No 1 Roger Federer, in contrast, needed just 62 minutes to get by 19-year-old Australian Bernard Tomic 6-2, 6-4 and book his spot in the quarter-finals.

Murray, the defending tournament champion who pulled out of last week’s Toronto Masters with a knee injury after his opening match, never looked himself as he was broken in the seventh game of the first set by Chardy, who is in the draw as a lucky loser.

Neither player could hold serve in the opening five games of the second set but Chardy held firm to go up 4-2 and never looked back in the 98-minute match. Chardy, ranked 38th, has been in good form of late beating American Andy Roddick in the first round in Cincinnati after defeating compatriot and world number six Jo-Wilfried Tsonga in Toronto last week.

The 25-year-old took full advantage of Murray’s less-than-potent serve and unforced errors for his first win against the Scot in five attempts.

“I didn’t serve particularly well. I got broken three times in the second set, which isn’t good enough. I broke him a couple of times in the second,” said Murray. “I had a lot of close games on his serve in the first and second set and didn’t convert enough chances, and, yeah, I didn’t serve well enough.”

Murray will head to the US Open, which starts on 27 August, with just three hardcourt games under his belt since his Olympic triumph on the grass courts at the All England Club but he says he is not worried about lack of preparation before Flushing Meadows.

“I won’t play any more matches. Going into the big tournaments, sometimes I’ve won tournaments in the build-up and it hasn’t helped me and then this year Wimbledon I lost in the first round at Queen’s and made the final there for the first time,” said Murray. “So it doesn’t normally have that much bearing. But, you know, obviously I would have liked to have done a bit better this week.”

Chardy will now next face Argentine Juan Martin del Potro who fought past Serb Viktor Troicki 7-6, 2-6, 6-1.

Federer will face American Mardy Fish who defeated Czech Radek Stepanek 6-3, 6-3 in a repeat of the 2010 final here.

“It’s his kind of surface, he’s at home in America and so I am going to have my hands full,”  Federer said of Fish.

Meanwhile, concerns over Rafael Nadal’s long-term fitness grew when the Spaniard formally pulled out of the US Open.

The world No 3, who completed his set of grand slams by winning in New York in 2010, was forced to miss the Olympics and the Masters Series events in Toronto and Cincinnati with a knee injury, and is still not ready to compete.

Nadal said: “I am very sad to announce that I am still not ready to play and have to withdraw from this year’s US Open in NYC.

“I am sorry since I always found great crowds and great support, but I have to continue with my recuperation and preparation to be ready to play in the right conditions.” While the announcement will come as a big disappointment to the tournament and Nadal’s many fans, it is not unexpected. The 26-year-old has not played since his shock second-round defeat by Czech Lukas Rosol at Wimbledon in June.