Rafael Nadal loses to Juan Martin del Potro in Shanghai Rolex Masters upset Juan Martin del Potro celebrates his victory over Rafael Nadal in the Rolex Masters. There will not be a 39th instalment, not yet, in the prolific series between reinstated world No.1 Rafael Nadal and the man he usurped. Novak Djokovic reached the Shanghai Rolex Masters final safely enough, but the unexpected sting in the semi-final tale came with Juan Martin del Potro's stunningly brutal upset of the Spaniard he had hailed pre-match as "unbeatable." The only man not named Nadal, Djokovic, Roger Federer or Andy Murray to win a grand slam singles title since 2005 bludgeoned the thundering forehand that anchored his 2009 US Open triumph, the 6-2, 6-4 result also sealing the Argentine's place in the eight-man field at the ATP World Tour Finals in London. "Very few times I played against a player with a level like today I played against," said Nadal, who hailed as "amazing" his opponent's powerful display. At the end I played against a player who served 80 per cent of first serves, who hit every ball as hard as he can I think, and with no mistakes. So I go home with the calm that I did all what I had to do and I played today against a player that was better than me tonight. Nadal said he would leave Shanghai "with the feeling that I didn't play bad. That's the real thing. Is fair to say that. I am enough humble to say that: that I played well, and I lost 6-2, 6-4. Having rebounded from his own shock loss to Lleyton Hewitt in the second round of the US Open by claiming the Tokyo title last week, del Potro burst to a 4-0 lead and never relinquished the advantage despite twice being threatened on serve early in the second set. His first win over Nadal in four years was - after his finals loss to Djokovic at the China Open on Sunday - just the second suffered by the Majorcan on hardcourts this season. And so, having never saluted in Shanghai despite an unrivalled record at Masters 1000 level - including five titles this year - Nadal will leave empty-handed again. He won eight of the pair's 11 previous encounters, but the ledger is now level at 4-4 on hardcourts, del Potro's favoured surface. "Always when you beat the No.1 player of the world, it feels something special on your mind, my feelings," del Potro said. My team feels unbelievable things. My family, friends. I mean, it's one moment so good to explain with words. I'm so happy, so exciting to enjoy a little bit this match. I know I have not many hours to be ready for the final against Djokovic. Del Potro's ongoing struggles with a wrist injury have been well-documented, but when healthy and on song the otherwise-gentle giant is an imposing force indeed. This was a gasp-worthy performance at times, just due to the sheer force of that forehand, his movement for a player of his height adding greatly to Nadal's degree of difficulty. At 25, the sixth seed is still the youngest member of an ageing top 10, and surely has more major successes ahead. "If he plays like he did this afternoon, of course, yeah," said Nadal. But is true that after the injury that he had, that is very tough to come back after injuries. Is true it was tough for him to find, well, the level of tonight. I don't know if he found before, but to find close to this level. If he plays similar to this level, for sure he's one of the biggest candidates to win a grand slam tournaments. He's able to do it. I'm sure he will win more. No such dramas - a second-set umpiring disagreement aside - for defending champion Djokovic, who advanced past Jo-Wilfried Tsonga 6-2, 7-5, to extend his fine record in China to 19 consecutive wins and three titles. Soon, perhaps, to be four. "It's very positive because most of the people would think after the fourth Grand Slam of the year is over, that somehow the season is finished in the minds of maybe people who are not following consistently the tennis season," said Djokovic. For me it's definitely not over. Unlike his latest reign at No.1, which ended on Monday after the most recent 48 of his 101 weeks in top spot. Chased becomes chaser. Does that change anything else? "To be honest, not a significant change in my approach to the tournaments," Djokovic said. I knew that the rankings are going to change, considering the fact what Nadal has achieved this year. It was a matter of a moment or a week or whatever when he's going to take No. 1 because he's had by far best results this year. I knew that, but I still keep on believing in myself and keep on working hard, being very much motivated to win every tournament that I play. It hasn't changed really. I'm still inspired to play my best tennis. That's how it's going to stay.