So now here's the actual story - Murray took exception to del Potro hitting hard up the middle with a passing shot of a weak volley. Expecting an apology (for what I have no idea) and not getting it, Murray took exception to it and began to shout out and congratulate himself on del Potro's errors. Murray's Mom joined in the cheering of his errors. Del Potro said nothing at the change over, and Murray again sought an apology for a perfectly legal play to which del Potro referred to him and his mother cheering his errors. It was to this point that del Potro said to Murray, "You're always the same...you and your Mom." Later Murray made patently false claims that del Potro was head-hunting on the pass, which isn't at all corroborated by this video:
http://www.youtube.com/v/q6psmRAm4tM&rel=1, which clearly shows that not only did he hit to the right of Murray (and not at his head) but that he the ball actually hit Murray's racquet. So why in the world he was expecting an apology is a big mystery. Perhaps he needed to invent a reason to be motivated, or perhaps he's so often in receipt of special dispensation for being the British #1, he has an inflated sense of entitlement and expect everyone - including his opponents - to cowtow to his every whim. Either way, the video shows that Murray is a liar for claiming del Potro hit at him, which he didn't, and is probably lucky that the umpire saved him the embarrassment of having to finish his thought when he said, "Do you want to speak about my Mum again?", because I'm certain he wouldn't have done a thing about it. To his credit del Potro stood his ground, and didn't apologize, and didn't continue the ridiculous argument with the umpire who began by rightly telling Murray his opponents have the right to hit it at the - EVEN THOUGH HE DIDN'T.