A tearful Rafael Nadal said "an important part of my life is leaving" after partnering Roger Federer for the final match of the Swiss great's career at the Laver Cup in London.

The last match of Federer's career saw him partner with his great rival Nadal to play doubles for Team Europe on Friday, taking on American duo Jack Sock and Frances Tiafoe at the O2 Arena.

Despite taking the first set, Nadal and Federer ultimately fell to an entertaining 4-6 7-6 (7-2) 11-9 loss before watching a series of tributes to the Swiss maestro, who also had an on-court interview and was embraced by his team-mates, opponents, family and friends.

Nadal, one of just two male players with more grand slam wins than Federer's 20 (22, also Novak Djokovic with 21), was seen to be in tears as he sat next to the retiring star during the post-match tributes.

During the match, he also showed signs of nerves due to the scale of the occasion and later declared he would hugely miss his long-time rival. 

"It has been a difficult day to handle every single thing, and at the end everything became super emotional," Nadal said. 

"For me, it has been a huge honour to be a part of this amazing moment of the history of our sport. 

"When Roger leaves the tour, an important part of my life is leaving too because of all the moments that he has been next to me or in front of me in important moments of my life.

"So, I have been emotional to see the family, see all the people. Difficult to describe, but amazing moment."