Rafael Nadal's season ended with a jolting loss to world number one Novak Djokovic on Saturday but after a worrying early-season rankings slide the Spaniard is happy to be back in the big league of men's tennis.

The 29-year-old will end the year as world number five and with his tally of grand slam titles stuck on 14 after failing to land one of the big four titles for the first time since 2004.

It is more than a decade since the Mallorcan left-hander ended a year ranked outside the top four but, having slumped to 10th in June after a demoralising loss to Djokovic in the French Open quarter-finals, he is heading back in the right direction.

This week at the ATP World Tour Finals he comfortably beat world number four Stanislas Wawrinka and number two Andy Murray before outlasting compatriot David Ferrer to complete a 100 percent record in the round-robin stage.

Djokovic proved a step too far in Saturday's semi-final, winning 6-3 6-3 with a sublime display of power and accuracy. The Serbian, though, has been too good for just about everyone this year and Nadal was upbeat about his prospects for 2016.

"I was not able to think about Novak for the whole season," Nadal told reporters.

"I have been playing in another league. "Seems like the last month-and-a-half, two months, I was in this league, I am in this top league. "So my motivation and my goal is try to keep being in that top league, that is the top five, top four of the world. That's my goal, and we'll see if I am able to keep doing this."

A fully functioning body will help in his mission as he nears his 30th birthday. Nadal missed the Tour Finals last year after appendicitis surgery, having missed three months of the season with a wrist injury following his loss to Nick Kyrgios at Wimbledon. He has also struggled with knee problems throughout his illustrious career.

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