Murray in fury after his mum is insulted

There were several heated exchanges, some of them seemingly prompted by Del Potro's criticism of Judy Murray's vocal support for her son.

The match boiled over as Murray scrapped to get back on level terms after losing the first set 7-5. Having already been given an official warning for an audible obscenity, what really fired him up were derogatory words uttered within earshot about his mum.

"I will accept lots of things, but not when someone insults my mum," the British No1 said.

"It was unacceptable. He can say what he wants to me but when someone says something about a member of your family, that's not cool. I told him to watch his mouth."

The match continued after both players had been warned by umpire Fergus Murphy and Murray levelled by taking the second set 6-4. But it ended abruptly when 6ft 5in Del Potro retired because of a back injury.

The 19-year-old Argentine had just been broken to go 1-0 down in the deciding set when he immediately called for the trainer at the change of ends.

Del Potro was in pain and he looked close to tears but after five minutes of treatment he admitted defeat. Murray will now play Swiss No2 Stanislas Wawrinka.