Even more gallingly for the King of Clay, the man who has replaced him in fourth in the ATP rankings is David Ferrer, his compatriot whom he dispatched 6-3 6-2 6-3 in the final at Roland Garros.
“It’s strange, no?” Ferrer said. “I lost the final against Rafael, but tomorrow, I’ll be No. 4. Anyway, I would change. I prefer to win here and to stay No. 5.”
The rather bizarre situation may have dire implications for Nadal ahead of Wimbledon, which starts on June 24, as he could well be seeded fifth in line with his ATP status. Wimbledon decide their own seedings but last year they mirrored the ATP standings identically.
If he is fifth seed then Nadal is likely to face one of Novak Djokovic, Roger Federer or Andy Murray in the quarter-finals, and may have to play all three of his big rivals in succession if he is to win Wimbledon for a third time.
The reason for Nadal slipping a place despite his crushing victory over Ferrer is that you earn no rankings points for defending a title under the rules of the ATP's 12-month rolling system.
Ferrer, meanwhile, improved on last year's performance when he lost to Nadal at the semi-final stage, so made ground on his fellow Spaniard, who is lying unexpectedly low in the rankings due to an injury-ravaged 2012.
However, Nadal now has the chance to enjoy a profitable second half of the year as he only competed in two competitions following the French Open in 2012 and therefore has plenty of points to accrue.
"There are still six months ahead of us," Nadal said. "I could be number one again if I continue at that level and if I'm not injured. But this is not 100 per cent sure.
"To be number one in this era, you need to play during the whole season. You have to play during the whole season and do well, because the other players are very competitive.
"They're going to be there. I need to keep winning a lot of points if I want to have any chance to be number one at the end of the season."
And what of his chances at Wimbledon?
"I will check all my body and I hope to be ready for Wimbledon," said Nadal.
"I don't play a tournament before Wimbledon so that's not the ideal situation before a Grand Slam like Wimbledon, which is on grass and with conditions that are very different.
"But if you can make it a few rounds, then the situation changes.
"I am taking everything a little bit more relaxed. Before, I wanted to practise every day a lot to be 100 percent sure that I am ready, but that's not possible any more.
"Hopefully it will be possible in the future, but not today. I think mentally I have accepted that situation.
"When you get more experience on tour, you probably don't need to practise as much as you do when you were a junior or when you are 19 or 20."