Naomi Osaka is showing appreciation for her boyfriend, rapper Cordae.
On Thursday, the four-time Grand Slam singles champion, 23, posted a sweet Instagram photo of the pair after the 2020 U.S. Open Women's Singles final in September, writing: "Appreciation post for the mister because I feel like it today 😂🙏🏾"
In the post, Osaka revealed that Cordae, 23, had dropped everything to join her in Flushing, New York, for the match after she told him she'd been feeling down.
"He stopped everything he was doing because I FaceTimed him a couple days earlier and said I was feeling sad and lonely in the bubble," she wrote in the caption. "I later found out that he hopped on a plane shortly after that call and then quarantined himself for a couple days in a hotel to see me and support."
"The funniest part is even after doing all this I'm still convinced he doesn't understand the rules of tennis lol," Osaka added — in the couple's interview for GQ's Modern Love issue last month, the rapper admitted that tennis is "not my sport."
Cordae also added to the magazine that cheering Osaka on at the 2019 U.S. Open was his "first tennis match ever."
On Thursday, Osaka included a video of Cordae sitting in the stands and proudly cheering her on during the 2020 U.S. Open finals match, where she defeated Victoria Azarenka.
RELATED VIDEO: U.S. Open Champ Naomi Osaka Couldn't Tell If Crowd Was Booing at Her: 'I Felt a Little Bit Sad'
Osaka secured the victory while wearing seven different masks with the names of victims of racial injustice ahead of her matches.
Among those she highlighted were Breonna Taylor, Ahmaud Arbery, and Trayvon Martin.
In December, she opened up for Vogue's January 2021 cover story about choosing to wear the masks, which she said helped motivate her to win.
"I was just thinking that I had this opportunity to raise awareness," Osaka told Vogue. "Tennis is watched all around the world, so people who might not know these names can Google them and learn their stories."
Continued Osaka: "That was a big motivator for me, and I think it helped me win the tournament."
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
"I don't think it matters if you're shy or not, or if you're introverted or extroverted. You're just there in the moment," she explained to the magazine. "When you see it in real life — so many cameras filming everyone, police with guns outside the city hall, the parents of other victims telling their stories — it kind of hits you differently."