Andy Murray, who sprinted into an early lead, was caught and then passed by Novak Djokovic 4-6, 6-3, 7-5 in two hours 34 minutes in group A of the Barclays ATP World Tour Finals.
It leaves the Scot needing to beat Jo-Wilfried Tsonga tomorrow to have any hope of progressing, yet he was so far in the lead in the match played on the Greenwich Peninisula he was almost in Peckham. Murray's demeanour after the match gave the best evidence that the Scot considered this an opportunity lost, particularly after taking the first set with an impeccable performance.
Chances were given to the world No.1 in the second set. It should be no surprise they were taken.
The Iron Men showed their mettle in endurance terms in the third set – coming in at 72 minutes – which nodded at the longevity of past encounters between these tyros.
An intriguing match can be summarised succinctly. Murray showed his power on serve and his focus to win the first set, dropping only three points on serve.
Djokovic, buoyed by a saved break point at 1-1 in the second set, shrugged off his problems with his backhand and took the next two sets and the match.
This brusque summation demands to be complemented by a precise description of the moments that decided the match.
Murray believes that two-and-a-half hours of sweat and the hardest of labour were decided "in the last two minutes". After swopping breaks in the decisive set, Djokovic broke from 15-40 and then Murray had 15-40 in the next game and failed to break. Djokovic therefore took the plaudits and Murray took the darkest of umbrage.
However, there were two other moments that were highly significant. The Scot forced a break point from Djokovic at 1-1 in the second set but the world No.1 saved it.
"I mean, he hit a drive volley on the back edge of the line. So what am I to do about that? Not much," said the Scot, not unreasonably.
If Murray had then served at 2-1 with a set in the bag then the match could have turned out differently. However, Djokovic makes a habit of stimulating such deliciously painful speculation in his opponents.
Much more curiously, the decisive break in the second set was effected after Murray served and volleyed. He does this as often as politicians admit they are wrong. It went about as well as one would expect of an uncharacteristic manoeuvre. Murray's volley drifted long and Djokovic had the breakthrough he craved.
Explanation? "When someone's blocking returns and chipping returns, normally you can get in close to the net and make it hard," said Murray. "He chipped the return, so I got the return that I wanted. I would have liked it maybe a little bit higher. But there are decisions you make in matches. If they come off, you get told you're a genius. If you miss them, then you're an idiot. That was just one of those ones that didn't work today."
But much else did work and there was even the heartening sight of Murray fighting back in the third when he looked to be drifting to defeat. Three straight games retrieved a break but Djokovic prevailed by taking his chances and surviving the opportunities he offered Murray.
This was the decisive factor in a match that never quite became an epic, even if the third set took more than a hour. It was, though, marked by both players' ability to return the ball from almost impossible situations.
Murray described himself and his adversary as the best retrievers in the game. The Scot, in a sickly yellow ensemble, could charitably be called a golden retriever. Djokovic, bedecked in black and tan, resembled a rottweiler as he caught and brought down Murray.
The match was played at its usual unrelenting intensity."Another great performance from both of us," was the verdict from an unabashed Djokovic. "I didn't expect anything other than a tough match that went down to the wire and was decided in the last point. It was important for me after dropping a first set to stay mentally tough and believe that I can get my opportunities, and when they're presented to try to step in and use them. That's what I've done." He said of Murray: "He made some unforced errors. He allowed me to get back into the match. Then I think it was quite even up to the last point."
A friendship forged on the junior circuit 14 years ago now encompasses a rivalry that Djokovic believes will evolve into something more substantial.
He is aware, too, that facing Murray represents an increase in his workload. Djokovic runs 3.8 kilometres on average in matches against the Scot, while other contests average 1.8km.
"It's something I always have in the back of my mind when I get to play Andy; it's going to be a physically very demanding match on any surface," said the world No.1.
"I had to hang in there. That's all I can say. That was my mindset, to try to stay out there, win every point that I play. That helped me."
Djokovic, too, was aided by his mantra that "a calm mind always wins". He now leads Murray 10-7 in their personal match-up but his mental strength has had to be augmented by sheer athleticism.
It was announced last night that the tour finals will remain in London beyond 2015. There was further evidence in the O2 Arena that Djokovic-Murray is also a drama that will run and run.