If Saturday's Doha final proved anything, it was how narrow the margins are between Andy Murray and Novak Djokovic. And thus, by extension, how tough this year could be for everyone else in the field.
Murray's 6-3, 5-7, 6-4 loss was essentially a matter of break-points won and lost. Had he taken advantage of a strong position in the sixth game of the deciding set, everyone might now be asking whether Djokovic is still languishing in the same psychological quicksand that dragged him down last year.
Instead, some confident souls were now declaring the reign of 'Sir Andy' to be at an end, only two months after he snatched the throne in Paris.
But the bookmakers paint a more nuanced picture. Before Saturday, they had Murray fractionally ahead in the odds for next Monday's Australian Open. Now Djokovic is back in front, but only by a nose.
"I still think I have a chance of winning the Australian Open after tonight," said Murray after this defeat. "I don't think that changes. It's disappointing to lose for sure. I have a chance to win the Australian Open still.
"I think physically it was a good test to start the year, and I did good here. My body feels all right just now, so that's positive. Still I think there are things I can do better. I wasn't that clinical on break points this week, which maybe comes with playing a few more matches."
This rivalry has moved through various stages. Murray was trailing slightly, by 11 wins to eight, when he underwent back surgery in the autumn of 2013.
After that, he resembled Leonardo di Caprio's character in The Revenant: initially immobilised, and then forced to endure a long, slow crawl back to full health and vitality.
While Murray dragged himself - figuratively speaking - across a frozen wasteland, Djokovic was cleaning up. In 2014, he won all four of their meetings on the tour. In 2015, the score was 6-1. And only last year did Murray pull the balance back close to parity, reaching Christmas with a 3-2 deficit.
Will their power struggle continue to shape the big events this year? The likes of Milos Raonic and Stan Wawrinka, who occupy the next two places on the world rankings, can hardly have been encouraged by Saturday's evidence.
Many of the rallies were hypnotically skilful. Both men kept redirecting play from crosscourt to down-the-line with little apparent effort, even though this is usually a high-risk ploy.
But it was Djokovic who was more accurate, launching a series of laser-like attacks down Murray's flanks. This victory would have held greater psychological weight had he closed out the match in the second set, when he held three match points.
Instead, Murray reeled off five straight games - a sequence that will give his coaches some useful pointers.
In the end, both men seemed to regard the evening as an excellent workout in the build-up to Melbourne. Note Murray's manner at the post-match handshake: he comes to the net laughing, perhaps in admiration of Djokovic's final scorching winner, and slaps his old adversary on the shoulders with the enthusiasm of a best man congratulating the bridegroom on his speech.
"I hope we are going to play against each other," said Djokovic later, when asked whether he expected to face Murray again in the Australian Open final. "We make each other work hard and improve and continuously work on our games and ourselves. We strive to get better, both of us."
Again, this was hardly what the other elite players would have wanted to hear. (Daily Telegraph, London)