Naomi Osaka announces split with coach Wim Fissette amid report of Patrick Mouratoglou pairing

Naomi Osaka's second tour with coach Wim Fissette is over, the former world No. 1 announced on social media Friday.

"[Four] years, [two] Slams and a whole lot of memories," Osaka wrote in a post to her Instagram stories confirming the split.

"Thanks Wim for being a great coach and an even greater person. Wishing you all the best."

The four-time Grand Slam singles champion hired the famed Belgian coach, who formerly worked with other major-winners including Kim Clijsters, Simona Halep, Angelique Kerber and Victoria Azarenka over the years, ahead of the 2020 season, and they stayed partnered in their first tenure until the summer of 2022. Osaka won the 2020 US Open and the 2021 Australian Open titles during their first chapter together.

They reunited last year, as Osaka trained to return to tennis after the birth of her daughter, Shai, with Fissette now-infamously leaving the partnership he had at the time with Zheng Qinwen to return to Osaka's team.

Read more: Zheng Qinwen buries past coaching split with Wim Fissette, praises Naomi Osaka

While Osaka has attempted to keep her expectations realistic for her comeback season, her results over the last eight months failed to reach her prior pedigree. She did not pass the second round at any of the four Grand Slam tournaments, though she did score her first Top 10 victory in four years over Jelena Ostapenko in the first round of the US Open. She lost in qualifying at the Cincinnati Open, the first time she played qualifying since February of 2018, and so far has reached just two quarterfinals in the 16 tournaments she's played this year.

She returned to the Top 100 in the WTA rankings on July 29, and is currently ranked No. 75.

Osaka's announcement came Friday in the aftermath of a report by Canadian tennis writer Stephanie Myles which said that Osaka was training with Patrick Mouratoglou on the campus of UCLA near Los Angeles, and that she had been negotiating with the former coach of Serena Williams and other high-profile stars since prior to the US Open.

Read more: Holger Rune and Patrick Mouratoglou are ending their player-coach relationship again

Aside from Fissette, Osaka had previously been coached by her father, Leonard Francis, since the age of 3, and also had a high-profile partnership with Williams' former hitting partner Sascha Baijin, with whom she was working with when she won the 2018 US Open and 2019 Australian Open titles.