ATP rankings: Roger Federer drops to No. 8; Stanislas Wawrinka up to third

Roger Federer is ranked as low as eighth for the first time since Oct. 28, 2002. (Mal Fairclough/AFP/Getty Images)

Roger Federer has slipped to No. 8 in this week's ATP Tour rankings, his lowest position since October 2002.

Federer fell two spots despite matching last year's semifinal appearance at the Australian Open. The previous No. 8, Stanislas Wawrinka, leapfrogged Federer and others after winning the Australian Open. Wawrinka jumped to a career-high No. 3, replacing Federer as the Swiss No. 1 and settling in behind No. 1 Rafael Nadal and No. 2 Novak Djokovic.

WTA rankings: Li closes in on No. 2

Federer wasn't the only member of the Big Four to tumble. Andy Murray also dropped two spots, to No. 6, after losing to Federer in the quarterfinals in Melbourne. Murray is out of the top five for the first time since August 2008. No. 4 Juan Martin del Potro and No. 5 David Ferrer now round out the top five.

In other rankings news:

• Grigor Dimitrov moved up from No. 22 to a career-high No. 19 after making his first Grand Slam quarterfinal.

• Stephane Robert, who reached the fourth round of the Australian Open as a lucky loser, rose 41 spots, from No. 119 to No. 78.

• Donald Young is up to No. 79 after a third-round run, his highest ranking since July 2012.

Here’s an explanation of the ATP's rankings system:

The Emirates ATP Rankings period is the immediate past 52 weeks. ... The year-end Emirates ATP Rankings is based on calculating, for each player, his total points from the four (4) Grand Slams, the eight (8) mandatory ATP World Tour Masters 1000 tournaments and the Barclays ATP World Tour Finals of the ranking period, and his best six (6) results from all ATP World Tour 500, ATP World Tour 250, ATP Challenger Tour and Futures tournaments.