Kei Nishikori, the 2014 and 2015 Barcelona champion, records his 20th victory at the tournament on Tuesday over Taylor Fritz.

Kei Nishikori lends a hand during Miami Unites Day at the Miami Open presented by Itau.

Kei Nishikori moves to 2-0 in his FedEx ATP Head2Head series with Adrian Mannarino on Sunday in Indian Wells.

Kei Nishikori defeats Benoit Paire at the Dubai Duty Free Tennis Championships on Tuesday.

Kei Nishikori will meet Benoit Paire in the first round of the Dubai Duty Free Tennis Championships.

Japan's Kei Nishikori routs Ernests Gulbis to reach the quarter-finals in Rotterdam.

Kei Nishikori will meet Ernests Gulbis in the ABN AMRO World Tennis Tournament second round.

Kei Nishikori defeats Pierre-Hugues Herbert in three sets at the ABN AMRO World Tennis Tournament on Tuesday.

Top seed Kei Nishikori will meet Open Sud de France runner-up Pierre-Hugues Herbert in the ABN AMRO World Tennis Tournament first round.

Eighth seed Kei Nishikori completes his fourth comeback from two-sets-to-love down on Monday at the Australian Open.

Kei Nishikori fought through two five-setters to begin the Australian Open.

Kei Nishikori survives another five-setter in Melbourne.

Kei Nishikori looks to reach his second Grand Slam final at the Australian Open this fortnight.

Kei Nishikori returns to the Australian Open with a win.

Kei Nishikori advances after falling behind two sets to love on Tuesday in Melbourne.

Japanese football star Keisuke Honda meets Kei Nishikori during a practice session at the Australian Open.

Kei Nishikori improves to 12-14 in tour-level finals after beating Daniil Medvedev to win the Brisbane International on Sunday.

Kei Nishikori defeats Daniil Medvedev in three sets to win the Brisbane International on Sunday.

Kei Nishikori beats jeremy Chardy to advance to his second Brisbane International final.

Kei Nishikori avenges his 2017 Brisbane final loss to Grigor Dimitrov on Thursday for a place in the semi-finals.

Rafael Nadal, Jo-Wilfried Tsonga, Andy Murray, Kei Nishikori and Nick Kyrgios will kick off the 2019 season in Brisbane.

Jo-Wilfried Tsonga, Rafael Nadal, Andy Murray, Nick Kyrgios and Kei Nishikori seek one of three ATP 250 trophies up for grabs in the season's first week.

Kei Nishikori celebrates his 29th birthday after receiving a cake during his press conference at the Brisbane International on Saturday.

Kei Nishikori fans cheer on the Japanese star during his match against Dominic Thiem on Thursday at the Nitto ATP Finals in London.

The eight singles players competing at the Nitto ATP Finals take the Jubilee line on the London Underground from North Greenwich station to Westminster station to attend the Nitto ATP Finals Official Launch presented by Moët & Chandon at London's iconic Houses of Parliament on November 9, 2018 in London, England. The tournament will be played 11-18 November at The O2.