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Rafael Nadal will drop to world number two after his loss at the Madrid Open quarter-finals to Dominic Thiem. In this picture, Rafael Nadal of Spain celebrates a point against Diego Schwartzman of Argentina in their third round match during day six of the Mutua Madrid Open tennis tournament at the Caja Magica on May 10, 2018, in Madrid. Clive Brunskill/Getty Images

The top spot in the ATP men’s singles rankings continues to swing from Rafael Nadal to Roger Federer with the two players trading spots yet again after the Spaniard’s loss in the quarter-finals of the Mutua Madrid Open on Friday. But the former can reclaim it before the start of the French Open on May 21.

The 31-year-old was the world number one for the last six weeks having taken over from Federer, who occupied the top spot for just over a week having taken over from the Spaniard, who started the 2018 season as the top ranked men’s singles player.

The Swiss became the oldest world number one in ATP history when he took over from Nadal in February after his title win at the Rotterdam Open. But his reign at the top was short lived as the Spaniard, who was sidelined with injury, took over again after Federer failed to defend his titles at the Indian Wells and Miami Masters Series tournaments.

Nadal returned to action at the start of the clay court campaign in Monte Carlo, and was defending 4,680 points on clay in 2018. He had to defend his titles in Monaco, Barcelona and Madrid to remain number one going into the French Open, but he failed as he fell in the final hurdle at the Spanish capital.

The 16-time men’s singles Grand Slam winner won in Monte Carlo and Barcelona, but fell in the quarter-finals to Dominic Thiem on Friday. It was Nadal’s first loss on clay in 357 days, the loss not only ended his 21-match unbeaten run, but also saw him lose his spot at the top of the rankings to his long-time rival.

Similar to Nadal, earlier in the year, the Swiss maestro will adopt the number one ranking on Monday without having played a single game since March 24 when he lost in the second round at the Miami Open. Federer was just 100-points behind the Spaniard, and owing to him not defending any points in the clay court season having skipped it entirely in 2017, he took over the number one spot when Nadal dropped 820-points by losing in the quarter-finals.

The number one merry-go round is set to continue for the rest of the season and it is likely to be between the two veterans, who are well ahead of the chasing pack at the moment. Nadal can reclaim top spot before the second Grand Slam of the year begins later this month.

The Spaniard lost in the quarter-finals of the Italian Open in 2017 meaning he has just 180 points to defend in Rome. He is currently 720 points behind Federer in the rankings and with him almost certain to play in the Italian capital; he can reclaim top spot by winning the title and hence gaining 820 points along the way.

He will then again have the 100-point advantage going into the French Open, where he will have to defend his title to remain at the top of the men’s ranking before the start of the grass court season, where Federer will have to defend just over 2,500 points.

Nadal and Federer have both indicated that the ranking does not concern them too much at this stage of the season, but, they will want to keep their advantage with both eyeing the year-end number one slot.