Nadal was eliminated in the group stage of the season-ending event on Friday (Saturday AEDT), but could still look back on a successful week after edging out Novak Djokovic for the year-end No.1 ranking.

To mark that achievement, Nadal was presented on court with a trophy by the ATP at the O2 Arena after he beat Stefanos Tsitsipas in his final round-robin match.

It's the fifth time he finishes the year as No. 1, and enough to make sure he leaves London with a feeling of satisfaction despite the early exit.

"Having this with me is something unexpected and very emotional for me," Nadal said.

"Honestly, after all the things that I went through in my career in terms of injuries, I never thought that at the age of 33 I would have this trophy in my hands again."

Nadal tied with Djokovic, Roger Federer and Jimmy Connors with five year-end No.1s, one behind Pete Sampras' record.

Djokovic's chances to overtake Nadal and equal Sampras' mark ended when he lost to Federer on Thursday and was eliminated.

At 33, Nadal is the oldest man to top the season's final ranking list. What's even more remarkable is that this one came 11 years after he first finished as No.1 in 2008 - a record-long gap.

"To have this trophy with me with this big gap between the first time until today, 11 years, is a big thing," Nadal said.

"I don't know if somebody did it or not, but it is something difficult, because 11 years since the first time until the fifth is a big number."

Nadal finished the group-stage with a 2-1 record but that wasn't enough to advance, after defending champion Alexander Zverev beat Daniil Medvedev in the final round-robin match to finish ahead of the Spaniard based on the tournament's tiebreaker rules.

If Zverev had lost, Nadal would have faced Federer in the semifinals for another instalment in their long-running rivalry.

Nadal also has two more Grand Slam titles to look back on this year, the French Open and U.S. Open, bringing his total to 19.

However he has never won the ATP Finals despite qualifying for a 15th year in a row.

Australian Associated Press