Naomi Osaka entered the court wearing a mask featuring the name of Breonna Taylor before her victory over Misaki Doi 6-2 5-7 6-2 in her opening US Open match.
The 22-year-old has emerged as a prominent sporting torchbearer in protests against racial injustice.
Osaka walked out to the court wearing a mask bearing the name of Taylor, a Black woman killed by police officers who burst into her apartment in March.
In a powerful post-match interview, the Japanese star explained that she has more masks ready to be worn as long as she progresses through the tournament.
"Actually, so I have seven (masks)," said Osaka.
It's quite sad that seven masks aren't enough for all the names. Hopefully I'll get to the final so you can see all of them.
Osaka initially pulled out of her semi-finals at the Western & Southern Open on Thursday to protest the police shooting of Jacob Blake, a Black man in Kenosha, Wisconsin.
She reversed her decision after tennis governing bodies suspended the tournament to join the protests.
With no spectators allowed into the Billie Jean King National Tennis Center due to Covid-19 health and safety protocols, large sections of seating in the Arthur Ashe Stadium court were covered with 'Black Lives Matter' banners.
Next up for Osaka in the second round at Flushing Meadows will be Italian Camila Giorgi, who earlier beat Alison van Uytvanck 2-6 6-1 7-5.
Naomi Osaka of Japan serves during her Women’s Singles first round match against Misaki Doi of Japan on Day One of the 2020 US Open at the USTA Billie Jean King National Tennis Center
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