Rafael Nadal falls out of top four for first time since 2005

Rafael Nadal is set to return in February and will make his Grand Slam return in Paris. (Jessica Kluetmeier/SI) If you're checking the new ATP rankings, don't

Rafael Nadal is set to return in February and will make his Grand Slam return in Paris. (Jessica Kluetmeier/SI)

If you're checking the new ATP rankings, don't adjust your eyes.

For the first time since May 2005, Rafael Nadal has slipped to No. 5. Nadal has been sidelined with knee tendinitis since losing to 100th-ranked Lukas Rosol in the second round of Wimbledon in June. He was set to return at the Australian Open but withdrew after contracting a stomach virus in December that derailed his training schedule. As a result, the 26-year-old Spaniard was unable to defend the 1,200 points he earned last year by making the final, allowing compatriot David Ferrer to pass him. Ferrer returns to No. 4 for the first time since September 2008.

Nadal is planning to return next week at the Vina del Mar Open in Chile. The tournament marks the first of three clay-court events for Nadal before he heads to the North American hard courts.

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The ATP Top 10:

1. Novak Djokovic

2. Roger Federer

3. Andy Murray

4. David Ferrer

5. Rafael Nadal

6. Tomas Berdych

7. Juan Martin del Potro

8. Jo Wilfried Tsonga

9. Janko Tipsarevic

10. Richard Gasquet

Other rankings movers: Sam Querrey is back in the top 20 and only four spots behind John Isner, who fell to No. 16 after skipping the Australian Open with a knee injury. Jeremy Chardy is up 11 spots to a career-high No. 25 thanks to his quarterfinal run in Melbourne. Ricardas Berankis, 22, made the biggest leap, surging 25 spots to No. 85 after successfully qualifying and making the third round.

As for the WTA, there was shuffling in the top 10. Victoria Azarenka retained her No. 1 ranking, but Serena Williams swapped with Maria Sharapova to become the new No. 2, just 355 points behind Azarenka. Williams and Azarenka are currently listed as playing upcoming tournaments in Doha and Dubai in February, but whether Serena holds that commitment is unclear in light of the ankle and back injuries she sustained in Melbourne.

Regardless, it's possible Williams could reclaim the No. 1 ranking without playing a match. Because of Azarenka's 26-0 start last year, she's defending a load of points after winning Doha and Indian Wells in 2012. She loses points if she fails to defend those titles, meaning Williams, who didn't play either event, could move ahead.

The WTA Top 10:

1. Victoria Azarenka

2. Serena Williams

3. Maria Sharapova

4. Agnieszka Radwanksa

5. Li Na

6. Angelique Kerber

7. Sara Errani

8. Petra Kvitova

9. Sam Stosur

10. Marion Bartoli

The most notable name absent? Caroline Wozniacki. Her fourth-round loss to Svetlana Kuznetsova dropped her to No. 11. Speaking of Kuznetsova, she jumped 25 spots to No. 50 after reaching the quarterfinals.