Roger Federer, Rafael Nadal BOTH outside top four

    Story highlights

    • Duo have been hit by injuries this season
    • The last of the two to win a major was Nadal in 2014
    • They hold a combined 31 grand slam titles
    • But Federer looking forward to January return

    (CNN)The passing of time -- and injuries -- can take a heavy toll on athletes but that said, tennis fans likely still did a double take Monday when they glanced at the men's rankings.

    For the first time since 2003, both Roger Federer and Rafael Nadal -- titans of the game who hold a combined 31 majors -- are outside the top four. Nadal sits at fifth, with Federer seventh.
      They've each been outside the top four previously but never in tandem since the last week in June 2003, when Federer held down the No. 5 spot and a teenage Nadal was 76th. Back then they weren't grand slam champions.
      But Federer would land his first major by the time the next rankings were released in early July -- triumphing at Wimbledon -- and the Spaniard would follow suit in 2005 by capturing the French Open, the start of an unblemished four-season reign at Roland Garros.
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      Together they took part in what many consider to be the greatest tennis match of all-time, a five-set battle at the All England Club in 2008 when Nadal edged the Swiss 9-7 in the fifth set of the finale.
      Their contrasting styles -- the power and left-handed spin of Nadal versus the smooth, attacking, all-around game of the right-handed Federer -- had onlookers savoring every matchup.
      But now Federer is 35 and Nadal 30, with both struggling to win majors ahead of the likes of Novak Djokovic and Andy Murray. The last of Federer's 17 came at Wimbledon in 2012, while the last of Nadal's 14 resulted at the French Open in 2014.
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      Injuries

      Federer has fallen outside the top four in what has been, by far, his most challenging season physically.
      He needed surgery for the first time in his career when he hurt his knee while running a bath for his twin daughters in January. Then his run of 65 straight appearances at majors concluded when he bypassed the French Open due to a bad back.
      He re-injured the knee in a five-set defeat to Milos Raonic in the Wimbledon semifinals, subsequently making the difficult decision to sit out the remainder of the campaign, including the Olympics and US Open, to recover.
      Nadal, meanwhile, admitted to a loss of confidence and his once fearsome forehand has faltered. He exited in the first round at the Australian Open to Fernando Verdasco, blowing a 2-1 lead in sets, but underwent a renaissance on his favored clay, securing back-to-back titles in Monte Carlo and Barcelona in April.
      Just when it appeared as if Nadal had a realistic chance to earn a 10th French Open title, he pulled out of the Paris grand slam in the first week because of a left wrist injury.
      Returning for the Olympics and winning gold in doubles while making the semifinals in singles for a much needed jolt of confidence, Nadal relinquished a break lead late in the fifth set and was ousted by Lucas Pouille in the fourth round of the US Open -- the lone grand slam where he and Federer have never faced off.
      Last week at the China Open, Nadal was upset by Grigor Dimitrov after winning their previous seven tussles, his serve punished by the Bulgarian.
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      Motivation

      In positive news for Federer, however, his comeback is "on track." He is scheduled to compete at the Hopman Cup in January, a precursor to the Australian Open.
      "I can't wait to get back to Australia, and to Melbourne for the Australian Open," Federer told the Australian Open's website Sunday. "I've been working extremely hard and am on track to come back fit, super strong and healthy to play firstly at the Hopman Cup in Perth, and then at the Australian Open.
      "My team tells me I'm on schedule and the promise of getting back on court and competing again is very exciting -- I've missed it so much. My motivation and love of the sport is as strong as ever and I'm really looking forward to heading down under to see all my Australian fans."