By Rohith Nair and Uday Sampath Kumar

BENGALURU, Sept 2 (Reuters) - The end of Serena Williams' glittering tennis career will have little to no impact on the American's brand value and her earnings from endorsements could even surge post-retirement, industry experts told Reuters.

Williams appeared to suggest last month that she would end her playing career at the U.S. Open, although she was a bit more vague about her intentions after her rousing first-round victory at Flushing Meadows in front of a celebrity-packed crowd.

Her third round loss to Australian Ajla Tomljanovic on Friday night, however, was likely her final Grand Slam match in a sport Williams has dominated for over two decades.

Sportswear giant Nike has said it will continue to partner with Williams, who turns 41 later this month, after her retirement. Other major sponsors are likely to follow suit.

"While Serena's on-court visibility will fade ... I don't see any drop in her brand value," said Bob Dorfman, sports marketing analyst at San Francisco's Pinnacle Advertising.

"More than a tennis superstar, she's a legitimate icon," Dorfman said. "The highest-earning female athlete of all time will surely remain a high-powered brand, even after putting down her racquet."

The only way Serena's brand value will fade is if she decides to stay out of the spotlight, said Lisa Delpy Neirotti, director of sports management programs at George Washington University.

"But if she becomes a voice of some cause, if she stays relevant and in front of her fan base, then her value goes up," Neirotti added.

"She's been such a powerful player on and off the court ... I think she'll be relevant in social causes."

MAINSTREAM RECOGNITION

While several elite male athletes have forged successful post-playing career brands, Williams' accomplishments, including 23 Grand Slam singles titles, position her well ahead of other female athletes in terms of appeal to major sponsors.

"As no other active female player is close to her level of accomplishment, everyone coming up in women's tennis will continue to be compared with Serena for a long time to come," said Phil de Picciotto, founder and president of sports agency Octagon.

NBA great Michael Jordan showed that athletes can earn more in retirement than during their playing days, while the injured Roger Federer still tops the list of the world's highest-paid tennis players despite 14 months of inaction.

Few women athletes have had lasting appeal to sponsors after retiring. But Williams, who has earned $35.1 million this year to edge out former men's world No. 1 Rafa Nadal ($31.4 million) and Novak Djokovic ($27.1 million), should be an exception.