'I kept fighting right to the end' - emotional Nishikori retires

After losing to Tiafoe, Nishikori did a lap of honour of the main showcourt in Tokyo - the place where he won the title in 2012 and 2014.

A video featuring Djokovic, three-time Grand Slam champion Andy Murray and 1989 French Open winner Michael Chang, congratulating Nishikori, was also played.

"Your resilience and fighting spirit, to always come back after a lot of adversity, is really commendable and admirable," Djokovic said.

"We had some great battles all over the world. I'm really glad you're ending your career in your town, your country, in front of your people.

"You're going to get the farewell you absolutely deserve."

Nishikori started playing aged five and moved to Florida as a 14-year-old to train.

He won 12 ATP Tour singles titles in his career and claimed 40 victories over top-10 players.

He was the first Japanese man to reach the top 10 of the world rankings and inspired numerous players, including four-time major champion Naomi Osaka.

His 72.5% win-rate in deciding sets is the third best in ATP Tour history, behind only Bjorn Borg (73.4%) and John McEnroe (72.8%).