Andy Murray's latest epic clash against Novak Djokovic may have been a great spectacle, but the Briton needs to show more composure as a worrying run of losses creeps in after his great triumphs.
Murray was destined to be another British also-ran until his defeat to Roger Federer at Wimbledon showed he could mix it with the greatest all-time players in the biggest matches.
He bettered that in some style, gaining revenge over Federer at the All England Club for the Olympics, before storming to a thrilling US Open victory against that man Djokovic, in what is destined to become one of the biggest rivalries in modern tennis.
But since his record-breaking success at Flushing Meadows, Murray has slipped back into his old ways.
His defeat to Milos Raonic in the semi-finals of the Japan Open came after a tight match, sure, but the Canadian is nothing more than unpolished potential, while Murray chucked away a third-set lead, two match points, and his racquet in what can only be described as a full-scale implosion.
He then fell to Djokovic in a quite remarkable Shanghai Masters final, blowing no less than five match points as his friendly foe took a small measure of revenge for his Olympic and US losses.
And of course we have his latest Nole opus, at the World Tour Finals in London's O2 Arena, an amphitheatre more suited to their gladiatorial style of combat than the genteel encounters of Murray's British predecessors.
A fantastic first set was followed by an error-strewn second that Djokovic almost took by default, before Murray regained focus while a break down in the second, only to blow up again.
What stood out for Tramlines in this latest defeat was when, with Murray chasing a second break late in the set, we saw an example of the British number one being exceptionally harsh on himself after an understandable miss.
At 5-5 in the third, Murray had done incredibly well to reach a Djokovic drop shot but, off balance, could not quite keep his flick in play. It would have put him two break points up but he almost beat himself up with his own racquet in frustration. The US Open Murray would have used it as motivation to get a break point at the second time of asking.
It's a slightly worrying sign that, apparently having learned to channel his anger correctly under Ivan Lendl, he is letting old habits creep back into his game.
It may not be a full-scale reversion though. Remember, Murray lost to Jeremy Chardy in the third round at Cincinnati. Chardy, while a decent player, is the very definition of a 'random punter' and had no right to beat Murray at a tournament he was defending.
Murray then went on to claim Britain's first men's Grand Slam in the Open era.
Lendl, and by default Murray, only cares about the Slams. Murray has won everything else, and nothing else matters.
Perhaps he has been advised to use all other tournaments — even the Masters Cups and Tour Finals — as outlets for his fiery temper, channels for his natural aggression and tendency towards public self-flagellation. It certainly seemed that way in Cincy, and before the French Open and Wimbledon.
Perhaps he is using these tournaments as extended training exercises, working out the knots in his game under reasonable pressure, with the focus on achieving perfection in the Slams.
There is also the added physical dimension to Murray. Since Rafa's decline in fitness, Murray has moved into pole position in the stamina and strength stakes, maturing into arguably the best all-round athlete on the Tour. He has turned a previous weakness into a strength, and almost prefers the 'best of five' format now, as he is able to maintain consistency even when Djokovic starts to flag.
Maybe he is mentally on holiday after completing his main job of the season in London and New York; the unconscionable errors — the underhit drop-shots, the listless forehands — hint at a mild disinterest.
But whether he progresses at the O2 or not, if Murray is to become one of the true world greats he must iron out the errors and tendency to implode, and resume his Djokovic rivalry in Melbourne, ideally with a second Major crown at stake.