Wimbledon 2013: Tandil Tower has to hope 13 is unlucky for Novak Djokovic

Novak Djokovic: The top seed will play his 13th consecutive Slam semi-final against Del Potro (Getty images)

A list of head-to-head results against Novak Djokovic does not make good reading for many players. In the case of semi-final opponent Juan Martin del Potro, the score is a stark 3-8, and one of Del Potro's three successes was on a retirement.

Yet for anyone intent on focusing on the positives, as tennis players have to be, those other two wins are worth hanging on to; for one was at Wimbledon itself, and earned an Olympic bronze medal and the other was the most recent encounter between the pair.

On Court One last August, Del Potro was very much second favourite, not least because he had just come through the longest match in Olympic history, beating Roger Federer 19-17 in the third set. Yet resilience, as he also demonstrated in recovering from a sickening fall on an already injured knee before beating the fourth seed David Ferrer here on Wednesday, is one of his great qualities. Thus it was that he matched and then defeated Djokovic 7-5, 6-4 on either side of a torrential downpour in their only previous meeting on grass at the Games.

Four Djokovic victories followed in the next four meetings, from Cincinnati to Dubai, but at Indian Wells in March there was another upset when Del Potro's win from a set down in 96F heat was the Serb's first loss in 21 matches.

"Was a close match," is how Djokovic remembers the Olympics. "Del Potro is a great player. He has struggled with injuries in the last few years but every time he comes back very strong because he has this talent. Quite flat shots from both sides round the baseline and he can move quite well round the court for his size. He's very tall so he'll use that serve as a powerful weapon. And of course the forehand, his signature shot."

It was that "signature" that the 6ft 6in Argentine inscribed on Centre Court two days ago, "my best forehand ever" as he called it, which together with a stunning serve throughout proved too much for Ferrer.

Remarkably, since his early fall looked so serious, Del Potro seemed not to suffer at all from any problem with the knee as the match wore on. Whether or not it was due to what he called the "magic pills" administered on court by the doctor, the only effect was psychological and once he had convinced himself that he could put sufficient weight on the leg to serve and hit as powerfully as ever, the physically smaller Ferrer was in trouble.

Today he did not extend himself in practice out on the Aorangi Park courts, but he clearly does not wish to make an issue of the wounded knee. "I have experience about injuries," Del Potro said. "It's the semi-finals of a Grand Slam. All players feel something, some pains, it's normal. You have to be strong more than the rest. I will need to be 100 per cent against him. He's the No 1, he's a former champion here."

The 24-year-old, known as "The Tower of Tandil" after the area of Buenos Aires from which he hails, now faces the Tower of Power who, like him, has reached the last four without conceding a set; it is apparently the first time that has happened in a men's semi-final here and illustrates how strong and consistent each man is on serve.

Djokovic, conceding only four inches as opposed to Ferrer's nine, should not have quite the same problem, although he will need to live up to his reputation as the best returner in the sport. He is playing his 13th consecutive Grand Slam semi-final, which might trouble a superstitious man, though he laughed it off in modestly admitting what a long way there is to go before matching Federer's record of 23.

There is no Federer now, of course, his defeat like that of Rafael Nadal having smoothed Andy Murray's path to the last four. The Centre Court crowd, doubtless giving Murray a better chance were he to meet Del Potro in the final, will offer the Argentine plenty of backing for all Djokovic's popularity. But it will still be a shock if Del Potro can draw sufficient inspiration from London's Olympics to be stepping out again here at 2pm on Sunday.

Get ready for a final scorcher

Temperatures on Centre Court could soar as high as 30C for the men's final on Sunday, but any suggestion the roof could be closed to protect the players from the scorching sun was knocked back today. The All England Club will, however, pull the roof forward slightly to provide shade for the royal box.

You can follow live, game-by-game coverage of Novak Djokovic v Juan Martin del Potro by clicking here