There will be no farewell tour.

“I don’t feel I need to go on the court for the entire world and every fan to know that this is my last time on the court,” Sharapova said. “Even when I was younger, it was not the way I wanted it to end.”

Sharapova said she knew it was time to retire as she flew home to Los Angeles from Australia. Kobe Bryant’s death in a helicopter crash on Jan. 26 made it even clearer.

“We were supposed to see each other like three days after the crash,” said Sharapova, who explained that Bryant had been an “incredible sounding board” throughout her career.

This time, she said, she had reached out for help in coping with her physical deterioration.

“I think we all seem at times in our journey like larger than life because of what we do, but everyone at the core is incredibly fragile,” she said of Bryant. “And if anything it just opens up your eyes to what really matters in life, so that was a moment where I had a really good think about my future as well.”

A 6-foot-2 Russian who punctuated her flat groundstrokes with piercing shrieks, Sharapova made one of the most extraordinary journeys in sports. If not for the Chernobyl nuclear disaster, she would surely not be a tennis star. Her parents, Yuri and Yelena, were living in Gomel in present-day Belarus in April 1986 when the reactor exploded in nearby Chernobyl. They eventually fled to Nyagan in distant Siberia to live near family. Sharapova was born there in April 1987, but Yuri soon moved the family to sunnier Sochi on the Black Sea, where he discovered tennis and passed it on to his only child.

In 1993, when Maria was 6 and post-Soviet Russia was in turmoil, she and her father moved to Florida with less than $1,000 in Yuri’s pocket. Martina Navratilova had noticed Maria’s potential at a Moscow clinic and recommended that she train abroad.

It was, in retrospect or not, a wild gamble. Sharapova, who was separated from her mother for more than two years because of American visa restrictions, showed remarkable steel, drive and talent as she worked her way to the top at IMG Academy in Bradenton, Fla.