
Together they hold 31 majors, but these are tough times -- relatively speaking -- for Roger Federer, left, and Rafael Nadal, right.

This week, and for the first time since 2003, Nadal and Federer are outside the top four in the rankings.

Injuries have played a big part. Federer needed surgery when injuring his knee while running a bath for his twin daughters after his Australian Open ended.

Illness then surfaced and Federer's run of 65 straight appearances at majors ended when he missed the French Open because of a back problem.

He returned at Wimbledon and was close to making the final. But he lost to Milos Raonic in the semis and re-injured his knee. He then decided to skip the rest of the season to recover.

Nadal, meanwhile, began the year by playing well in Doha. But then he exited in the first round of the Australian Open to fellow Spaniard Fernando Verdasco in five sets.

He gradually rediscovered his game and landed consecutive clay-court titles in April. However, the Spaniard hurt his left wrist and pulled out of the French Open -- he is a record nine-time champ at Roland Garros -- in the first week.

Skipping Wimbledon, Nadal came back at the Olympics in Rio and won gold with pal Marc Lopez in the doubles while making the semis in singles.

The roller-coaster ride continued: Despite the momentum, Nadal fell to Lucas Pouille in the fourth round of the US Open. Just like against Verdasco, he led by a break in the fifth.

And then last week, Nadal suffered his first loss in eight matches against Grigor Dimitrov at the China Open, and in straight sets.