Serena Williams’s comeback from the birth of her first child has taken another setback after the 23-time grand slam-winner was knocked out of the Miami Open, then stormed away from the venue.

The former world no. 1, unseeded after taking 13 months maternity leave, was convincingly beaten in straight sets by Japan’s Naomi Osaka on Thursday (AEDT).

Osaka, 20, defeated Williams 6-3 6-2 in just one hour and 17 minutes.

Williams, 36, was also reportedly fuming after the loss, with reports she stormed off and left the tournament site in a car straight after the match, refusing to give a press conference.

Under the Women’s Tennis Association’s (WTA) guidelines she will be fined as a result.

I'm not sure there will be a press conference with Serena Williams today. She has already left the tournament site in a car #Miami

— Stuart Fraser (@stu_fraser) March 21, 2018

https://twitter.com/Mike_Dickson_DM/status/976582549333008384

It was Williams’ fourth match and second tournament appearance since the birth of her first child, Alexis Olympia Ohanian Jr, in September.

She later released a statement to the WTA, saying: “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.”

Her defeat comes after the Miami Open director said seeding rules for players coming back after maternity leave were a “punishment” and “should be changed”.

Osaka, world no. 22, was also unseeded at the tournament but was in red-hot form after claiming victory her first WTA title at Indian Wells earlier this month.

Naomi Osaka won the BNP Paribas Open in Indian Wells in early March. Photo: Getty

Williams made her return to the WTA Tour at the same event, before losing to her sister Venus Williams in the third round.

It was the famous sisters’ earliest meeting in a tournament since the second round of the Australian Open in 1998.

Serena is currently ranked world no. 491 after her lengthy absence, although she can use a protected world standing to enter up to eight tournaments during a 12-month period, meaning she can avoid qualifying rounds.

However, the loophole does not apply to seedings.

Special seedings were once applied to players returning from long spells on the sidelines, but that rule has been abolished by the WTA.

Former tennis player and tournament director of the Miami Open James Blake said Williams was harshly treated by the WTA ahead of her match with Japan’s young gun.

He called it “a kind of punishment”.

“I think they are going to start talking about changing the way some seedings are done and I hope they do,” Blake told AFP on Tuesday.

“For someone who goes on maternity break, they should be protected. These kind of things shouldn’t happen. She has won this title so many times that she needs protection.

“It’s not as if she left because of injury and lost her passion for the game. She had a kid which we should all be celebrating so when she comes back there should be a grace period where she can still be seeded.

“It’s a kind of punishment which is tough. I hope they revisit those talks although it will be too late for her unless she decides to have another child.”