ANDY Murray has reached the stage of his career where even a defeat to a resurgent 14-time Grand Slam champion can spark the uncorking of a million conspiracy theories. This 6-4, 6-1 loss to Rafa Nadal in the second match of his ATP World Tour Finals campaign was uncharacteristic of his work during a stellar year and means the World No 2 still has a job to do before he can consolidate that position at the year's end for the first time in his career. But surely there was more to it than that?

Perhaps the 28-year-old was distracted by the unruly straggles of hair protruding from his fringe which caused him to produce a pair of scissors from his kit bag when trailing 2-1 in the opening set and give himself an impromptu trim? Maybe it all boiled down to a flaw in the format of the Tour finals, that regardless of yesterday's result, Murray would always have another chance to progress from the round-robin phase on Friday against Stan Wawrinka? Or perhaps the manner in which this second set got away from him after a taut 57-minute opener was in fact deliberate, the alleged lack of desire he showed to win merely indicating that a semi-final assignment against Roger Federer supposedly represents an easier route to the final than taking on World No 1 Novak Djokovic?

The 28-year-old from Dunblane listened to all this before dismissing it with the scorn it deserved. “I think that Roger plays great in this event," said Murray. "He’s won it, what, six times, played some unbelievable matches here. He obviously played great tennis yesterday [when he beat Djokovic]. This isn’t for me about who’s better out of Roger and Novak because things can change on a daily basis.

"I've never looked at any matches like that," he added. "You certainly don't want to lose to one of the guys that you're competing against in the biggest events for the biggest titles quickly in the second set. I'm obviously disappointed with the way the match finished. I'm not trying to finish second in the group. I'm trying to win every match I play."

In fact the real reason for the defeat was more basic than that: the Scot's own level of performance, and particularly a rather unconvincing display on serve. While Nadal has upped his game considerably since being humiliated by Murray on clay in the final of the Madrid Masters - the most recent of the pair's 21 previous meetings - the World No 2 was left chiding himself for a first serve percentage which stood at just 43%. With Nadal winning two thirds of all points on his second serve, including a liberal sprinkling of double faults, that quickly became a recipe for disaster. Murray has improved his second serve immeasurably during 2015 but such improvements weren't so obvious here.

The unwritten assumption going in was that Murray, having played the stronger tennis all year, would operate at a level Nadal couldn't reach. It was an inference which seemed to be coming true when the Scot pounced on a nervous opening service game from his opponent in the very first game of the match.

But the Spaniard broke straight back, and generally played the more aggressive, forceful tennis for the remainder of the set. While Murray bravely saved two break points for 4-4, he was eventually broken to love to surrender the first set 6-4.

With little sign of an upswing in those service statistics as the match went on, the second set got away from the Scot in a hurry, with the only conspiracy theory with any currency whatsoever the fact that, when push comes to shove, fears about pushing his body to breaking point ahead of the Davis Cup final were perhaps playing somewhere in the back of his mind. Having chased down one Nadal drop shot to play a bravura winner down the line, Murray appeared to be feeling tightness in his quads and hamstrings but downplayed such fears afterwards. "I pushed extremely hard to pick up the ball," he said. "I was just a bit tight on that one run and it was fine after that."

The other main issue left to ponder afterwards was how close Nadal was to returning to the top table of world tennis. "Obviously for a few months this year he was struggling for form a little bit," the Scot added. "But I think, you know, almost every player goes through that at some stage during their career. A lot of the media had a lot of doubts about him. But I think a lot of the players still felt, provided he stayed injury-free, that he would raise his game again and compete at the top. I'm sure, even now, but by the beginning of next year, he'll be playing at a very, very high level again."