Top 4 players with the most 5-set wins in the 2019 Grand Slam season

Kei Nishikori - 5

Kei Nishikori

Kei Nishikori stared at a disappointing first-round exit at the Australian Open when he trailed Polish qualifier Kamil Majchrzak by two sets. But the Japanese quickly regrouped and reeled off the next two sets for the loss of just two games en route to sealing a 3-6 6-7 6-0 2-0 3-0 victory when Majchrzak retired.

The tables were almost turned on Nishikori in the next round when Croatian veteran Ivo Karlovic recovered from a two-set deficit to force a fifth set. However, Nishikori regrouped in time to triumph in a historic 'first to 10' fifth-set tiebreak to reach the third round.

A straight-set win over Joao Sousa carried the Japanese to the fourth-round where Pablo Carreno Busta led by two sets, only for Nishikori to win the match in another 'first to 10' fifth set breaker.

In the process, Nishikori emulated Roberto Bautista Agut as the only other player at the 2019 Australian Open to win three five-set matches. However, the exertions took a toll as Nishikori retired down 1-6 1-4 against eventual winner Novak Djokovic in the quarterfinals.

In the third round of the French Open, Nishikori trailed Serbia's Laslo Djere by two breaks in the fifth set. But incredibly, the Japanese recouped both of the breaks and prevailed 8-6 to reach the fourth round where he faced Frenchman Benoit Paire.

Nishikori led Paire by two sets to one and saw match points in the fourth set tiebreak come and go as the Frenchman forced a fifth. Nishikori trailed 3-5 in the decider but reeled off the final four games of the match to reach his fourth Roland Garros quarterfinal (lost to Rafael Nadal).

The victory over Paire was Nishikori's fifth five-set win of the year. In the process, the Japanese improved his incredible fifth set-record to 23-6 (0.79), which is the best fifth-set win % for any player with at least 20 five-set wins in the Open Era - behind Bjorn Borg's 0.82 (27-6).

Since his last five set-defeat (against Federer in the fourth round of the 2017 Australian Open), Nishikori is on an eight-match five-set win streak.