IT feels more like a pre-final than a semi-final. A bit like Old Firm matches in football, Rafa Nadal versus Novak Djokovic is one of those sporting match ups which never gets tired, even if it is played six times a season. Today’s instalment on Centre Court will be the 52nd absorbing episode of a long-running series which has occurred more frequently than any other fixture in the open era.

The scores on the doors give Djokovic 26 wins to Nadal’s 25 but this afternoon’s meeting promises the start of a new phase in the rivalry. While the Mallorcan has taken the only two encounters which have been contested since the onset of the Serb’s elbow problems at the start of 2017, both of them on clay, the World No 1 knows he will be taking a giant leap forward if he can back up Wednesday’s five-set tussle with Juan Martin del Potro by defeating Djokovic to book a place in his first final since finishing runner up in 2011. Who was the opponent that day? Yeah, you’ve guessed it.

Yet should Djokovic prevail, this match would seem even more of a staging post on his comeback from the wilderness. At his best, Djokovic was perhaps the only man on the planet who could feel pretty good about their chances of overcoming Nadal on any surface.

That four-set victory on finals day in 2011 – one of six meetings that calendar year, all taken by Djokovic – was the first of three consecutive major finals, all of which went the way of the Serb. We should settle in for a long evening - that 2012 Australian final win was a five-set encounter which lasted five hours 53 minutes (a record for a Grand Slam final), just 24 hours after the Serb had played for four hours 50 minutes to get past Andy Murray. Djokovic also has only Robin Soderling for company in the list of men to have taken the Spaniard’s scalp at Roland Garros, a straight sets quarter final win in 2015

No wonder Nadal knows this won’t be a straightforward day at the office, even if it is his first Grand Slam semi-final since the 2016 US Open. “It is always a big challenge to face Novak,” said Nadal. “He is one of the more complex players that I ever saw on our sport. It is always a big test. You know that you can’t win against him if you don’t play very well. You need to be ready for it. But I hope to be ready to play very well, and let’s see what’s going on. I know he’s playing very well. I’ve seen his matches. He’s playing great.”

Overshadowing a match-up of such giant proportions is a tall order, but Kevin Anderson and John Isner will give it their best shot. Whether it is the 6ft 8in South African or the 6ft 10in American who prevails in the day’s first semi-final, the winner will be the tallest man ever to grace a men’s singles final at Wimbledon. While Nadal has never lost against either and Djokovic has a sizeable winning record against both as well, conditions are favouring the big servers this year. While all four men are in their 30s, these two are playing the best tennis of their careers, with Anderson hoping to reach his second Grand Slam final, following his straight sets loss to Nadal in the 2017 US Open. Isner has 161 aces this fortnight, while Anderson merely has 123.