At the Laver Cup last month, Carlos Alcaraz complained that the tennis schedule is "going to kill us". But this week the Spaniard, who has only played two ATP events since the US Open, is playing the £11.5m Six Kings Slam in Saudi Arabia where Rafa Nadal and Novak Djokovic are also competing for the £4.6m first prize.

Rafael Nadal starts his pre-retirement farewell tour against Carlos Alcaraz on Thursday at the Six Kings Slam.

Carlos Alcaraz, winner of four majors, crushed the Dane Holger Rune (6-4 and 6-2) in his first game and now will face Nadal in the semi-finals of the tournament with this set to be the last ever game between the two idols of Spanish tennis, with the Davis Cup in Malaga next month set to mark Nadal’s definitive farewell from the sport.

Rafael Nadal starts his pre-retirement farewell tour against Carlos Alcaraz on Thursday at the Six Kings Slam, and Novak Djokovic faces Jannik Sinner at an exhibition event that awards money but no ATP ranking points and is Saudi Arabia's latest foray into tennis.

The kingdom is putting on the richest tennis exhibition in history, but its wider ambitions in the sport have contracted.

One by one, they pull up at the St Regis Hotel in Riyadh. Jannik Sinner, Carlos Alcaraz, Rafael Nadal, Daniil Medvedev and Holger Rune have arrived — only Novak Djokovic is yet to join the biggest stars in men’s tennis in accepting flowers,

The Six Kings Slam is the most lucrative exhibition tennis tournament ever, taking place in Riyadh, Saudi Arabia, as part of the country’s annual sporting season.