Our reporter in Belgrade, Chris Bowers, analyses the difference between the two teams during Argentina's Davis Cup by BNP Paribas World Group semifinal victory over Serbia, largely the performance of Juan Martin del Potro.
The Serbia v Argentina tie was expected to be all about the new US Open champion Novak Djokovic. When he walked out for his singles on Sunday, he was given a hero's reception by a packed and ecstatic Belgrade Arena. But the tie ultimately proved to be about his predecessor-but-one, the 2009 US Open champion Juan Martin del Potro.
Del Potro seemed to have the world on his racket strings when he beat Roger Federer in a five-set final at Flushing Meadows two years ago. But a wrist injury at the start of 2010 deprived him of almost the whole of last year, and it has been a gradual ascent up the rankings since the start of this year.
Yet this weekend he proved he is back. His ranking may still be closer to 20 than to 10, but rankings indicate consistency rather than the ability to win a big match, and del Potro has regained the ability to beat the top players on any given day.
He described his straight sets win over Janko Tipsarevic on Friday as 'one of my best wins of the season', and while his 76(5) 30 win over Djokovic on Sunday was completed by the Serb's retirement with a lower back injury, del Potro clearly thought he was playing well enough to win even against a fully fit opponent.
In retrospect, Djokovic's involvement in the semifinal resembled the legendary Spanish figure El Cid, the 11th century warrior who was put into battle despite being wounded because his reputation alone was likely to instil fear into his Moor opponents.
Despite being held back until Sunday, Djokovic's appearance at the start of the fourth rubber suggested the semifinal was headed for a decisive fifth match, in which Tipsarevic would have started a slight favourite against David Nalbandian. But del Potro was not to be fooled by the warrior's reputation, and once the Argentinean had won the opening set, Djokovic looked a beaten man.
The irony is that Serbia's hold on the Davis Cup has come to an end when the country has unprecedented success in the rankings and the Grand Slams. It paraded the same four players who won the Cup last year, but with its singles players ranked 1, 13 and 15, and the doubles player Nenad Zimonjic third in the doubles rankings.
Yet those numbers mask a tired and injured Djokovic, a second player in Tipsarevic who is still recovering from a gruelling run to the US Open quarterfinals, and a fragile Victor Troicki whose confidence is low after a poor hard court season. Against an Argentinean team that has discovered its belief in away ties, the Serbs were ripe to be picked off.
The question now is whether Argentina has any realistic chance of a first Davis Cup title in what will be its fourth Final. Playing away to Spain doesn't make things easy, and it's tempting to pencil in Rafael Nadal's two singles matches as home wins. That would leave the visitors needing to beat Spain's No. 2 player twice, and win the doubles.
It's a tall order, but by no means impossible. If del Potro can keep up the form he showed this weekend, he has at least a 50:50 chance against Spain's second player (presumably David Ferrer). The one worrying element for Spain from its win over France was the doubles pairing, which looks an Achilles heel that could be exploited by Argentina if Nalbandian can pair up with a partner he's comfortable with, perhaps Eduardo Schwank who was overlooked for the semifinal against Serbia.
That might give Argentina a 2-1 lead going into the final day, and if the 2011 Davis Cup by BNP Paribas were to come down to a live fifth rubber, anything could happen. Del Potro beating Nadal in the fourth is also not entirely out of the question, as he is likely to be the fresher of the two men at that time of year.
For Nalbandian, who will be 30 on New Year's Day, this could be the final realistic chance of a Davis Cup winner's medal. For del Potro, there is a sense that if it doesn't happen this year, it could happen in the next few years, as Argentina have another healthy crop of youngsters looking to break through. Either way, the legacy of this weekend in Belgrade could well be that Argentina have rediscovered their self-belief, and have their eyes set on a first Davis Cup title.