Serena Williams has been hit with a not too insignificant fine of $1,000 by the WTA after failing to attend a mandatory press conference following her first round exit in the Miami Open to Naomi Osaka on Wednesday.

Williams was in no mood to speak to the press following the match and left Crandon Park as soon as the game was finished.

Whilst the fine may not put a huge dent into Williams' bank, it will probably have knocked her pride slightly and it could have been worse.

Currently unranked, the fine could have been as much as $5,000 had she been ranked inside the top four in the world, something she's gotten used to over her illustrious career.

But, she can probably be forgiven for her slightly patchy form since returning to tennis.

She did of course miss most of 2017 due to her pregnancy, and it will take time for her to settle back into the game and hit the form that won her eight trophies from 2002-2015.

This is only Serena's second tournament of the year, the first being at Indian Wells where she was beaten by her overshadowed sister Venus.

Following the missed press conference in Miami, Williams said this: "Every tournament is an opportunity for me to better understand the areas I need to improve to be my best.

"Naomi played a great match and I learn something each time I play. I look forward to continuing my return by progressing every day. I'm so grateful for my fans who continue to support me every step of this incredible journey."

Osaka won the match 6-3, 6-2 to force Williams out of the tournament, much to the surprise of many tennis fans.

Her Miami debut was 20 years ago and she had never exited before the fourth round in all her visits to the tournament.

Maybe, just maybe, she's not quite ready to return just yet.