Hello and welcome to LIVE coverage from world number one Novak Djokovic's Cincinnati Masters quarter-final clash against big-serving American John Isner.

So it is John Isner who is through to the semi-finals to face Juan Martin Del Potro tomorrow, knocking out world number one Novak Djokovic in three sets.

DJOKOVIC 6-7(5) 6-3 5-7 - GAME, SET & MATCH! Isner rattles a forehand passing shot winner down the line to deny Djokovic on his first game point and then finds a backhand stop volley winner on the second to level up at deuce. A backhand error from Djokovic then hands Isner a first match point, which the Serb saves with an ace down the centre of the court. Ouch. A double fault from Djokovic hands Isner a second match point and this time he does get it when Djokovic nets a backhand!

DJOKOVIC 6-7(5) 6-3 5-6 - Isner races through another quick service hold, battering down a couple of aces for good measure, forcing Djokovic to serve to stay in the match for a second time. Can the world number one force the tie-break?

DJOKOVIC 6-7(5) 6-3 5-5 - Despite being on the receiving end of a time violation warning Djokovic holds with an ace. He brought up game point with a sensational run into the net, backhand pick-up and forehand passing shot winner, the crowd's applause of which drew the time violation!

DJOKOVIC 6-7(5) 6-3 4-5 - Another fairly easy service hold goes the way of Isner, who leaves himself potentially just one game away from the semi-finals. Djokovic will have to serve to stay in this match after the change of ends.

DJOKOVIC 6-7(5) 6-3 4-4 - Djokovic posts a very quick love service game this time around, sealing the game with a big serve and a cross court forehand winner.

DJOKOVIC 6-7(5) 6-3 3-4 - Isner's turn this time to come through a tough service hold as he secure the game from deuce, finding a big first serve exactly when it matters to keep the pressure on Djokovic.

DJOKOVIC 6-7(5) 6-3 3-3 - Djokovic is not having it all his own way on serve today as Isner again pushes him, this time to 30-all, before the Serb can hold and level up once more.

DJOKOVIC 6-7(5) 6-3 2-3 - Isner races through a love service hold to sling all the pressure back over to the net at Novak Djokovic, who has to serve second throughout this final set.

DJOKOVIC 6-7(5) 6-3 2-2 - A backhand error from Djokovic allows Isner to level at deuce but a big first sevre from the Serb followed by a backhand cross court error from the American and Djokovic has the hold that allows him to level once more.

DJOKOVIC 6-7(5) 6-3 1-2 - Isner eases through another service game, holding for the loss of just the one point when Djokovic slices a low backhand into the net.

DJOKOVIC 6-7(5) 6-3 1-1 - A break point goes begging for Isner as he runs around the ball to hit a forehand, only to make the error and Djokovic goes on to hold from there with a deep sliding serve that Isner can only return into the very bottom of the net.

DJOKOVIC 6-7(5) 6-3 0-1 - Isner clenches his fist in the direction of his team after coming through a tough opening service hold from 30-all to deny Djokovic the early break. The Serb was looking to climb all over the Isner serve but couldn't quite manage it and Isner opens the final set.

DJOKOVIC 6-7(5) 6-3 - SET! A big first serve, a bigger forehand down the line and an easy cross court forehand winner seal the set for Djokovic as he holds to 15 to level up at one set apeice.

DJOKOVIC 6-7(5) 5-3 - Isner holds to 15 when Djokovic sends a fairly routine forehand sailing long of the baseline. The world number one will have to hold if he is to serve out this second set.

DJOKOVIC 6-7(5) 5-2 - Isner backs away from a serve in order to take it on the forehand, firing it back across court and drawing the forehand long down the centre of the court from Djokovic to level up at deuce. Another forehand error from the world number one on the next point and suddenly it's break back point to Isner. The chance goes begging with a backhand long though and Djokovic goes on to hold. Isner will have to serve to keep this set alive after the change of ends.

DJOKOVIC 6-7(5) 4-2 - Ace number four from Isner helps him hold despite a tough game in which Djokovic pushes him to deuce. But the American is not forced to face down a break point and he remains just the one break adrift.

DJOKOVIC 6-7(5) 4-1 - Djokovic is quick to race through a hold to 15 to comfortably maintain his break advantage, a big serve and a cross court forehand doing enough to seal the game in his favour.

DJOKOVIC 6-7(5) 3-1 - Isner gets his serve back on track with a hold to love sealed with a service winner to get his side of the scoreboard ticking over once more.

DJOKOVIC 6-7(5) 3-0 - Djokovic has only the one blip (a backhand wide down the line) in an otherwise perfect game as he seals the hold with a service winner to consolidate the break in this second set.