After being broken in the first game, a fan shouted "Naomi, you suck" and Osaka could later be seen wiping away tears.
After the match, the event's 2018 champion addressed the crowd on center court, saying the incident reminded her of when Venus and Serena Williams were booed at the tournament in 2001.
"I've been heckled before and it didn't really bother me," Osaka said while holding back tears.
