The top two players in the world Rafael Nadal and Roger Federer lock horns in the final of the World Series finals at the O2 Arena in London.

FEDERER WINS! The world number two races through his service hold to seal victory with two crisp first serves, followed by a volley into the open court to move to 40-0. The Swiss misses a volley at the net, but fires a forehand down the line to clinch victory! What a win for Federer!

BREAK! Federer drills a sumptuous backhand winner down the line to move to 0-30 and, after grabbing a point back with a well-worked rally, Nadal plants a backhand into the net to concede two break points. Federer seals the break with a powerful forehand to close out a second break, and now he can serve out for the match!

Federer begins his service game impeccably, but Nadal pegs him back to 30-30 with two fierce forehands down the line! Federer plants a forehand into the open court to clinch a long rally, but fires another long as the game drifts into deuce. But the Swiss shows his composure once more to close it out with two pinpoint serves.

BREAK! Federer does superbly to retrieve three improbable balls at the back of the court before Nadal fires a smash down the line, and a half-volley sees the Spaniard move to 30-15. But Federer suddenly seizes the initiative with a stunning array of attacking blows, and the Swiss breaks from deuce - astonishing stuff!

Federer holds in confident fashion, and Nadal is certainly not moving as freely as usual as the pair exchange extended rallies time and again. The Swiss holds the ascendancy in this final set.

What a game! Nadal claims an incredible rally with a forehand down the line after somehow retrieving what looked like being a winner from Federer. The Spaniard is put under immense pressure, but he holds to level at 1-1.

Federer goes wide with a forehand in an extended rally which sees Nadal make the first move in this third set, but the Swiss responds with three first serves to move to 40-15, and take the game with a fourth.

Who are you backing for the final set? Post your predictions and comments below! It is all to play for as the music blares out at the O2 Arena - whose going to clinch the first break?

SET NADAL! Nadal hammers a fierce forehand cross court to set up two set points at 40-15, and Federer cannot do anything to stem the flow of momentum his opponent is creating! The world number one finds a big first serve, and takes the second set in just 34 minutes...

Federer holds with ease, but the Swiss knows that he needs to throw himself into the next game and prevent his opponent from holding to clinch the second set! Can the Swiss find a timely reponse?

Nadal holds to move to within a game of the second set, and this match is heading to an inevitable and thrilling final set! Federer gives his all to stop the Spaniard in his tracks once more, but Nadal holds firm.

Federer rattles through an imperious service hold to love, and that is incredibly efficient from the world number two as he immediately turns the pressure straight back on to his opponent.

Federer is utterly relentless as he forces Nadal to 30-30 with a forehand down the line, but a fortunate net cord enables the Spaniard to hold from 40-30. Closing out this set is not going to be easy for Nadal, and Federer is sure to give it everything.

BREAK! You just knew it wouldn't be advantage Federer for too long, and Nadal takes a vicious assault on his opponent's serve to break and assume a 3-1 lead! The Spaniard is faultless as he crushes two forehand winners, and now the Swiss will have to respond.

Nadal moves in court to bludgeon a short ball down the line for a winner to move to 40-15, but Federer wins another epic rally to pin his opponent back once more. The world number one won't be denied, however, and he holds as Federer goes long with a backhand.

Brilliant from Federer! Nadal drops two pretty tame forehands short, and Federer ruthlessly pummels each down the line in uncompromising fashion! Nadal fires a warning shot with a backhand pass cross-court to peg Federer back to 40-15, but goes long with his return to concede the game.

Nadal begins the second set in confident fashion, and the Spaniard holds comfortably with three very fine first serves. Can Federer settle as quickly?

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SET FEDERER! Nadal goes wide with a backhand after two fine first serves from Federer, and the Swiss now has three set points. A stunning forehand cross court gives the world number two the opening set 6-3, and in just 32 minutes! Nadal has it all to do now.

BREAK! Nadal finds a pinpoint serve which clips the line to move to 30-15, but the Spaniard in the lurid pink shirt then slices a backhand long. Nadal fires one forehand inside the line, and one beyond it to see the game move to deuce, and Federer plays two exceptional rallies to clinch the crucial break!