US Open 2018: 5 things to know about first-time Grand Slam finalist Naomi Osaka

3. Her sister is also a tennis player

Naomi (left) with her sister Mari

Mari Osaka, Naomi's older sister, is also a pro-tennis player, who also represents Japan. Just like the Williams sisters, the Osaka sisters also practice together and Naomi has said it many times that her sister's presence on the circuit does help her.

Mari is currently ranked No. 367 in the world, her progress having been stalled by injury.

Like Serena and Venus, the Osakas learned the game on public courts and were coached by their father. On numerous occasions, the two sisters have been compared with the Williams sisters and have been expected to make waves in the tennis circuit.