Nadal came into the contest with a 15-7 head-to-head advantage over the Serb, but Djokovic led the way on the hard courts, 7-4.
Their last four meetings had been on hard courts, two of them indoors, and the Serb had won three of them. But their only meeting this year was in the US Open final, the Nadal won in four sets.
As if that was not enough, the line was drawn in the sand for end-of-week qualification. With Tomas BerdychÃ¢â‚¬â„¢s defeat of Andy Roddick, Djokovic only had to beat Nadal to guarantee a semi-final place. With the Roddick defeat, Nadal could not guarantee anything, even by beating Djokovic.
To add a touch of spice, both also had a point to prove. Djokovic went out at the round robin stage last year despite winning two of his three matches. Nadal caused a meltdown in the media by losing every match.
So the scene was set. Both men won their first matches, and both looked fit and healthy. The only form guide was the ease with which the Serb adapted to the London court like a duck to water. Of all the men in the tournament, he appeared to make the transition to the low and slow court the most easily.
In contrast, Nadal got off to a hesitant start. He is a player who likes time on the court and that is the one thing he lacked, having missed Paris with shoulder tendonitis. However, Roddick made sure he got enough action to sharpen up his timing and burnish the bullish attitude.
That improvement continued in what began as an intense and closely fought match. Djokovic threw down the gauntlet on his opening serve with a love game and then forced Nadal through a series of extended rallies to deuce. In a sign of things to come, though, the Spaniard produced his first 130mph serve to ace the game.
By the fifth game, Nadal was in aggressive form and won his first break point. Djokovic replied with an ace but suffered two more deuces, and an exchange of touch volleys went NadalÃ¢â‚¬â„¢s way. The break was made.
Djokovic made a swift reply, and his trademark backhand down the line gained him two break points in return. This time, an error from Nadal drew the set level at 3-3.
With 40 minutes on the clock already, the game of cat and mouse, attack and counter-attack, continued. Nadal won another break point in the seventh game, but failed to capitalise. As one man seemed to gain the advantage, his opponent snuffed it out.
Then the match took an unexpected turn that changed the momentum not just of the first set but of the entire match. Djokovic called a halt in the eighth game to summon help to retrieve a contact lens.
With the set level at 4-4, Nadal then had to sit out an extended break while Djokovic disappeared off court for additional treatment. The Serb afterwards asserted that, from this point on, he could not see the ball clearly, especially the return of serve: Ã¢â‚¬Å“I just could not play. The doctor couldnÃ¢â‚¬â„¢t see anything, but one minute I had two lenses and then there were three!Ã¢â‚¬Â
The match edged to 5-5 just as a full hour clicked up, but as the two re-engaged, the body language said it all.
DjokovicÃ¢â‚¬â„¢s head dropped as he struggled to hide his growing frustration at another break point chance nullified by a big Nadal forehand. Djokovic had two more chances, but Nadal resisted. A cross-court winner closed out the set 7-5.
The changeover was a picture of contrasts. Djokovic had yet more treatment to his eye while Nadal casually changed his shirt, towelled himself down, and bounced to the baseline for second set action.
The errors began to leak from DjokovicÃ¢â‚¬â€20 of his 31 tally were struck in the second set. Nadal, meek as he is off court, is neither compassionate nor easily distracted in the heat of battle. He raced to a 4-0 lead before Djokovic could hold a service game, which he did with arms held aloft in salute.
In essence, though, the contest was over. An imperious overheadÃ¢â‚¬â€a reminder that Nadal is becoming an accomplished all-court playerÃ¢â‚¬â€won his fifth game, and he served out the sixth with ease.
Nadal afterwards extended his commiserations to Djokovic, but was quick to comment on the high level of play he displayed: and he was right. He even took the admonishment of the umpire to speed up his play with a pinch of salt: Ã¢â‚¬Å“I said, it shouldnÃ¢â‚¬â„¢t be a problem because this is a friendly match. If [Djokovic] has a problem, I donÃ¢â‚¬â„¢t mind waiting, and he doesnÃ¢â‚¬â„¢t mind either.Ã¢â‚¬Â
The Djokovic take on the match was one of barely-suppressed anger: Ã¢â‚¬Å“I really donÃ¢â‚¬â„¢t feel like talking about itÃ¢â‚¬â€this never happened in my life before. I just could not play. Unfortunately it happened in a very important match.Ã¢â‚¬Â
Despite the loss, the Serb is still in the competition but will need to be seeing the ball very well against Roddick. Nadal, though, is almost across the finishing line for the semi-finals.
Who he plays there will be determined by the final round. David Ferrer and Roddick languish at the bottom of their pools and are as good as out of the running. As for the rest, it really is still up for grabs.
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BIOGRAPHY: Ethan Hazard
BIOGRAPHY: Daniel Sturridge