Nadal picked up a fourth consecutive French Open title with a straight-set win Sunday over Ferrer. It was his Open-Era record eighth championship at the event, where he has an overall record of 59-1.
Nadal is 43-2 this year, with seven titles and two runner-up finishes in nine appearances.
However, he was protecting the champion's points from 2012 while Ferrer was marking a career first in making it to a major tournament final. That allowed Ferrer to net enough points to climb to fourth in the rankings, pushing Nadal to fifth.
"It's strange, no? I lost the final against Rafael but tomorrow I am going to be No. 4 and him No. 5," Ferrer said. "I prefer to win here and to stay No. 5."
That quirk in the rankings could soon resolve itself because Nadal will be protecting just 45 points the rest of the year after missing the second half of 2012 with a knee injury. No. 1-ranked Novak Djokovic, in contrast, won 6,800 points from Wimbledon through the end of 2012. A return to No. 1 is a distinct possibility for Nadal.
The only other change in the Top 10 came for Jo-Wilfried Tsonga, who played Ferrer in the semifinals in Paris. He is now seventh in the rankings, forcing Juan Martin del Porto, who didn't play in the French Open due to illness, to eighth.
The grass court season begins this week. Federer, No. 3 in the rankings, and ninth-ranked Richard Gasquet lead the field at the Gerry Weber Open in Germany. No. 2 Andy Murray, sixth-ranked Tomas Berdych, Tsonga and del Porto are in the draw at the Aegon Championships in London.
The men's world tennis rankings, with rankings points:
1. Novak Djokovic, 11,830
2. Andy Murray, 8,310
3. Roger Federer, 7,640
4. David Ferrer, 7,220
5. Rafael Nadal, 6,895
6. Tomas Berdych, 4,515
7. Jo-Wilfried Tsonga, 4,155
8. Juan Martin del Potro, 3,960
9. Richard Gasquet, 3,090
10. Stanislas Wawrinka, 2,810