Naomi Osaka said she is still coming to terms with her US Open victory a day after defeating Serena Williams in the final.

"It still doesn't really feel that real," said Osaka. "I think right now what I'm feeling is very tired. So hopefully as that wears off then I'll start feeling more happy."

On Saturday, the 20-year-old became Japan's first grand slam singles champion by thumping Serena Williams 6-2 6-4 in a match that will go down as one of the most controversial major tennis finals in history.