Andy Murray and Novak Djokovic had met six times in 2012 prior to today's clash at the ATP World Tour Finals in London.
Having both won three apiece, one of the duo was going to take a 4-3 lead in their head-to-head record.
As it was, it was Djokovic who claimed the spoils despite losing the opening set to world number three Murray.
Read our minute-by-minute updates of the match below.
Afternoon all. Now, I don't like to big up matches too much just incase they let us down. However, I'm pretty sure this one won't. Right now, it's got to be the biggest match-up that the sport has.
Roger Federer and Rafael Nadal may have something to say about that statement I guess, but the simple fact is that Murray and Djokovic have produced some of the most memorable moments of 2012. To be honest, it would be the most fitting final for this competition.
As mentioned in the introduction, these two have met on six occasions - with every match being a memorable one for one reason or another.
It all started back at the semi-finals of the Australian Open in January. It was Murray's first Grand Slam with Ivan Lendl as his coach and the change almost had a great effect. As it was, Djokovic won through 6-3 3-6 6-7(4) 6-1 7-5 in a gruelling battle.
Murray gained an element of revenge on the hard courts of Dubai, before Djokovic went 2-1 in front thanks to a success in Miami Open final.
Then came Murray's moment! He defeated Djoko 7-5 7-5 in the semi-finals of the Olympic Games in London on his way to winning gold. Next up was the US Open final. Murray had the burden of having never won a Grand Slam on his shoulders. However, what unfolded was a fantastic 7-6(10) 7-5 2-6 3-6 6-2 success for the Scot that went on until the early hours in the United Kingdom.
"It should be a tough match. We've had some tough battles and there is a good chance it could go that way today. I've got to focus and try and get the win," Murray has just told Sky Sports News.
Meanwhile, Djoko has said: "It's a big challenge to play Andy. We've had some good matches. He's been on top of men's tennis for the last couple of years. He's playing great but I feel I'm hitting the ball well to."
The pair are now heading to the court. Murray will be introduced first...
And what a reception the Olympic champion receives from his home crowd! They're going to be right behind him today.
Having said that, Djokovic's greeting was not too shabby either! He's an extremely popular player around the world.
Well, well. Murray wins the toss but opts to receive. The Scot is obviously keen to secure an early break of Djokovic's serve. Janko Tipsarevic did that against Roger Federer yesterday and it back-fired on him. Let's hope for Andy's sake the same doesn't happen here.
The duo are just going through some final serving routines. Not long now until we are off and running.
Right, here we go. Djokovic will serve first...
Djokovic sends the ball into the net with a loose shot and as a result Murray has an early break point...
BREAK! What a start to this match and what a fantastic point that was! Djokovic sends the ball down the line and has Murray scampering. The Scot's return draws Djoko to the net, but his return his high and Murray is able to power the ball beyond the reach of his opponent. Great tennis from both players.
That's the way to do it as far as Murray is concerned. He serves out to love in a game that included a stunning ace. Djoko looks a little shaken - he needs to settle.
And settle he has! The ball was finding the strings a lot better in that game, allowing him to force Murray back past the baseline. Still, Muzza has the crucial break.
Beautiful stuff from Murray brings up another love hold. Have to say that Djokovic is making a number of unforced errors down the backhand wing. That's not like him at all.
Murray can only find the net with a passing forehand stroke and gives Djokovic the game in the process. The Serb is still not firing on all cylinders though. However, we all know that he can turn it on at the drop of a hat.
Djokovic gets his first point on the Murray serve, albeit from a double fault, but the Scot is in cruise control to be honest. That game also included another ace - his second of the match.
Djokovic is still alive and kicking in this set. During one point in particular he had Murray on the run. Important service game coming up for Murray.
It was hard work, but Murray pulled himself through there. He served another ace, while his curling second serve also caused problems. Djokovic is now serving to stay in the set.
We are at deuce in this ninth game...
Delightful from Murray. Just delightful! He returns a shot that he has no right to, then shows great skill to play a drop shot that Djokovic can only stand and admire. Set and break point...
But Djoko responds, as he does so often when his back is against the wall. Deuce.
Great character from Djokovic. He looked like losing that game but he was at his brutal best to recover. He's got to break Murray now though or the set is gone.
Three set points Murray...
SET! It's been a fantastic serving performance from Murray. Even his second serve, which at times has hampered him, has been very, very good. Djokovic has shown what he can do in patches, but it's all been a bit scrappy from the Serb. This is by no means over though.
Here comes the second set. A frustrated looking Djokovic will serve...
That is just what Djokovic needed. It's a comfortable service game for the world number one. Murray produced a couple of unforced errors in that one and vented his frustration rather loudly!
ACE! A powerful ace from Murray brings up the hold. To be honest, Djokovic has not looked like breaking the Scot so far today. He also made two backhand errors in that game, taking his tally for the match up to 11. That's so unusual for him.
Big chance for Murray as Djokovic clips the top of the net and the ball bounces out. Break point...
It's a great serve and volley from Djokovic - the ball just clipped the line. That took guts! Deuce.
Hold! That's important for Djokovic. At break point down he cut a forlorn figure but he looks invigorated now. Could that be the turning point?
Murray's second serve is getting better and better. The curve he is getting on the ball is sending it into Djokovic's body and he has no answer. Another good hold for the Scot.
That's more like the Djokovic we all know. He served his first ace and outpowered Murray all around the court. Pressure now on Murray to hold.
Great net play from Djokovic brings up his first break point of the match. This is a big moment in this match...
BREAK! Murray tries his first serve and volley routine but his return is just too long and Djokovic goes two games clear. It will be interesting to see how Murray reacts now. He's had it all his own way for 70 minutes or so.
Murray fires wide while returning Djokovic's serve and with it could have gone his chances in this second set. Djoko was ruthless in that one. Even when he is not at his best he is a force to be reckoned with.
That is all Murray can do. He holds convincingly and as a result is making Djokovic serve for the set...
Three set points Djokovic...
SET! I said this game was by no means over and Djokovic has proved me correct - we are going the distance at the O2 Arena. Djokovic's serve improved greatly in that set and consequently he has grabbed a hold on the match. This is far too close to call.
Murray gets the decider underway...
That is really cheap from Djokovic. He's produced some really poor return of serves and in doing so has given Murray the lead. Very, very strange.
That was probably the best game of the match so far. Murray only got to 15, but he could have easily won it. As it was, Djokovic got the better of some long rallies - rallies that have defined the rivalry between the pair.
Three break points Djokovic...
Djokovic finds the net with the first. Still two remaining...
BREAK! It's advantage Djokovic as Murray goes long with the usually dependable double back-hand. The Scot is clearly frustrated with himself, which never seems to help his game.
A comfortable hold for Djokovic and this match seems to be slipping away from Murray at the moment. The crowd have also gone a little flat. He needs to inspire them somehow.
Break point Djokovic...
But Murray is let off the hook by Djoko, who fires wide into the tramline. It's important that the Scot holds. If he doesn't, it's game over.
That is a massive hold from Murray, who has kept himself in contention. Djokovic had his chances, but he spurned them. The crowd have sensed how important that was for Murray and are now trying to lift their man.
An error-strewn game from Murray makes it far too easy for Djokovic to hold. Time is running out for the world number three. He needs something special to happen, and quick!
Break point Djokovic. This is happening far too often from a Murray point of view now...
But it's poor from Djokovic, who drives the ball into the net. He seemed to be in too much of a hurry there. The second serve was only 84mph. Deuce.
Just when he looks down and out, Murray claws himself back in. Again he battles back from a break down to hold. Ideally, he needs to be getting into Djokovic's serve now.
Half a chance for Murray, who leads 15-30. The crowd try and lift him again...
Two break points Murray Quite simply, he has to take one of these!
Djokovic forces him wide with the first one. There is one left. What a massive moment this is...
BREAK! What a challenge from Murray. He insisted that Djokovic's cross court shot was out and HawkEye proved him right. That's fantastic from the Scot. He looked down and out. Game on!
It looked dodgy for Murray at 15-30 down. However, once again he showed his battling qualities to serve it out. I wasn't expecting to say this five minutes ago, but Djokovic will serve to stay in the match!
An opportunity for Murray as he leads 15-30 on the Djoko serve...
But he trips as he goes to retrieve a drop shot and he can only loft the ball wide of the court. How unfortunate. 30-30.
The chance comes and goes for Murray. It was awkward for Djokovic, but he scrapes through. Murray now to serve.
Two break points Djokovic. This set has been so unpredictable!
ACE! What a time to pull that out the bag. Murray still has one more break point to save though...
BREAK! Djokovic lets out an almighty roar as Murray fires long. He knows how big that break of serve is. The Serb will now serve for the match. Surely that's the end of the drama, isn't it?!
It's currently 15 all...
Djokovic finds the net. Make that 15-30 in Murray's favour...
SMASH! Great net play from Murray brings up two break points...
Djokovic saves the first having made Murray run all over the court. One more remains...
And a great serve from the Serb brings up deuce. Murray will be bitterly disappointed.
Match point Djokovic as Murray fires long...
GAME, SET AND THE MATCH NOVAK DJOKOVIC
Again Murray hits the ball too long and Djokovic has the victory. What a match! Djokovic looked done after the first set, but the world number one responded brilliantly. That's why he is regarded as the best about. That win has all but booked his place in the semi-finals.
For Murray, he will now have to beat Jo-Wilfried Tsonga on Friday to secure his spot in the final four. It's not ideal, but he is by no means in a bad position.
"We really pushed each other until the end. It could have gone either way. It was enjoyable to be a part of this match today. He was too good in the opening set. I had to be more aggressive and it changed when I got the break in the second set," Djokovic tells Sky Sports News during his post-match interview.
That's just about all we have time for this afternoon. However, we will back tonight to bring you live updates of the other group in this match - Tomas Berdych vs. Jo-Wilfried Tsonga. See you then.
