Djokovic has been in sublime form, winning all five of his matches at the All England Club without dropping a set.
Del Potro, seeded eighth, has also had a perfect progression through the draw, but serious questions have been asked about the Argentinian's fitness ahead of the opening match on Centre Court.
A knee injury he suffered against Grega Zemlja in the third round flared up again on Wednesday when he fell awkwardly on his left leg in his quarter-final win over David Ferrer.
Del Potro, wearing heavy strapping on the knee, could only practise for 40 minutes yesterday, but he was confident of being fit and focused for the match.
"I am okay," he said.
"I think I will be better for (the semi-final). I will think about the match, about Nole (Djokovic) and nothing else."
Del Potro came out on top in the pair's only meeting on grass last year, when the Argentinian denied the world number one a bronze medal at London 2012.
Djokovic's form through Wimbledon suggests he is playing much better than last summer, leaving Del Potro to tread carefully when asked about his chances of winning.
"It will be a difficult day but I will try to play better than (against Ferrer) and try to win," Del Potro added.
"I am confident at the moment with my serve and all my game.
"Nole is world number one. Not many can beat him and he is a big favourite for the tournament, but I will try to win."
One man backing Del Potro to do just that was compatriot David Nalbandian.
The former world number three was the last player from Argentina to reach a Wimbledon final back in 2002 and he said: "I'm really happy for Juan Martin because it's very hard to get to the semis at Wimbledon.
"I think that he has a good chance (of winning) because he can take take his experience of beating Djokovic on grass last year in to the semi."
With Rafael Nadal and Roger Federer already out, Djokovic, champion here in 2011, may not have a better chance to win Wimbledon again.
Andy Murray had a faultless run to the quarter-finals, but the second seed was heading into his semi-final against Jerzy Janowicz having just been taken to five sets by Fernando Verdasco.
While the British number one toiled on Centre Court two days ago, Djokovic had already finished his day's work. He was at his temporary Wimbledon base, posing for a picture in his golf gear, apparently ready to hit the course for a bit of rest and relaxation.
Djokovic has every reason to feel bullish. He has been in this situation before. The clash against Del Potro was set to be his fifth Wimbledon semi-final, and he is drawing on all his experience to keep his nerve while all those around him suffer.
"I'm trying to use that experience that I had in past, especially in this tournament in 2011, to feel comfortable and calm and confident towards the end of the major tournament," the top seed said.
"Now I'm in the semi-finals. Hopefully I can go a step further.
"I believe I can make it."