the doubles draw, teaming with Máximo González. They lost to Raven Klaasen and Michael Venus in the first round. At the Miami Open, seeded fifth, he lost his first match to Dušan Lajović. At the Monte-Carlo Masters, Nishikori was defending an appearance in the final, but lost to Pierre-Hugues Herbert in the second round. At Barcelona, he entered seeded fourth, defeating Taylor Fritz, Felix Auger-Aliassime and Roberto Carballés Baena, being defeated by Daniil Medvedev in the semifinals. At the Madrid Masters, he was seeded sixth. He defeated Hugo Dellien before losing to Stan Wawrinka in the third round. At Rome, he entered as sixth seed, defeating Taylor Fritz and Jan-Lennard Struff before losing to Diego Schwartzman in the quarterfinals. At the French Open, Nishikori was the seventh seed. He defeated Quentin Halys and Jo-Wilfried Tsonga before defeating Laslo Đere and Benoît Paire in tight five-set matches in the third and fourth rounds, respectively. In the quarterfinals, he was defeated in straight sets by defending champion Rafael Nadal, who went on to defend his title. At Wimbledon, Nishikori was seeded eighth. He reached the fourth round without dropping a set, defeating Thiago Monteiro, Cameron Norrie, and Steve Johnson. He dropped a set against Mikhail Kukushkin in the fourth round, but won the match in four, reaching the quarterfinals at Wimbledon for the second consecutive year. He was defeated in four sets by Roger Federer. He reached the third round at the 2019 US Open. 2021: Return, ATP 500 quarterfinal & semifinal, first top 10 win in 3 years Nishikori started his year playing in the 2021 ATP Cup, losing both of his singles matches to Daniil Medvedev and Diego Schwartzman. At the Australian Open, Nishikori lost in the first round to Pablo Carreño Busta in straight sets. Nishikori made his first quarterfinal since Wimbledon 2019 in Rotterdam, after beating 7th seed Félix Auger-Aliassime and Alex de Minaur. He lost to Borna Ćorić in two tiebreak sets. He also made the quarterfinals in Dubai, beating Reilly Opelka, 5th seed David Goffin and Aljaz Bedene. He lost to eventual finalist Lloyd Harris in three sets. Nishikori was seeded at an event for the first time since the 2019 US Open in Miami. Seeded 28th, he once again beat Bedene, but lost in the third round in three sets to Stefanos Tsitsipas. Nishikori's clay-court swing also showed progress of his return. His first tournament