Tokyo, Japan - Naomi Osaka was supposed to have played the first tennis match of the Tokyo Olympics on center court on Saturday, but the match was pushed back because she was chosen for "the greatest honor I will ever have": lighting the Olympic cauldron.

Speculation that the 23-year-old winner of four grand slam titles would have a role in the opening ceremony started as soon as it was announced on short notice that her first round match against China's Zheng Saisai would be moved to Sunday.

It turned out that the Japanese star was chosen for the biggest honor of completing the torch relay, and while the stadium was empty, billions watched her via television as she lit the cauldron.

"Undoubtedly the greatest athletic achievement and honor I will ever have in my life," Osaka said later on Instagram.

"I have no words to describe the feelings I have right now but I do know I am currently filled with gratefulness and thankfulness."

World number two Osaka is returning to tennis at her home Games after withdrawing from the French Open and not playing Wimbledon and stating mental health problems.

Osaka was born in Japan but moved to the United States at the age of three. Her mother is Japanese and her father from Haiti.

"The most important thing was to deliver a message of diversity and inclusion," opening ceremony executive producer Takayuki Hioki said.

"In the end we decided on her because she is a great athlete and she has been delivering a variety of messages so we thought she was the best person to be the final torchbearer. It was a decision that the whole organizing committee came to."