An attack of the grumps from Andy Murray? We ought not to be surprised. Perhaps more so that he acknowledges it for what it was, an unnecessary, focus-jeopardising distraction that could have cost him his place in the fourth round of the Pacific Life Open here had he not nipped it in the bud.

Murray was not at all happy with what occurred more than once during his 7-6, 6-7, 6-3 victory over Ivo Karlovic of Croatia, a player who is a 6'10" handful at the worst of times. He got very down on himself, something he has tried desperately hard to rid from his game since every match he played with Brad Gilbert in his coaching corner seemed to dissolve into a self-defeating rant against the world.

For Murray to admit to a disappointment with his attitude is an extremely significant step in his development. For him to play a third set as sublime as the one that ultimately got inside Karlovic's head, was just as important. Murray is a fascinating make-up, a player with so much going for him in terms of touch, craft, vision and skills, yet who imploded too often for his progressive good. Every time he got into one of his strops, you feared that it could cost him dear, because not many players over the years with the exception of John McEnroe and Jimmy Connors (and they were multiple grand slam champions and both world No1s) have been able to harness all that inner turmoil and turn it to their advantage.

Murray is not that good yet but one senses that corners are being turned. "It's pretty immature and something that is not very professional," he said. "I want to make sure it's something that I get out of my game because when you play against the best players, you need to be focused the whole way through the matches.

"I worked a lot on it and the end of last - sorry, at the start of this year. It's been way, way better. It's something I've decided I want to get out of my game and, hopefully (there is always a hopefully) I won't let it happen again because it's not the right thing for my tennis."

What should also be mentioned is that Murray played some quite exhilarating tennis, not least in the third set when he broke serve, resisted Karlovic's powerful riposte and went on to slam some wondrous ground-stroke winners beyond the big man's reach.

Murray is growing up in every way. It is a pleasure to see it.