Billie Jean King considers Venus Williams’ performance this past year to be inspiring, especially because she did not think Williams would be able to play singles after her medical scare last year.

At a press conference before the New York Empire’s 25-13 World Team Tennis loss to Philadelphia at the USTA Billie Jean King National Tennis Center in Flushing, King, a 39-time Grand Slam winner, said she thought Williams’ career was in serious jeopardy following her diagnosis with Sjögren’s syndrome.

“I was concerned with her Sjögren’s challenge,” King said. “I thought maybe she would be lucky to play doubles.”

Last September, Williams’ confidential medical records, which were being held by the World Anti-Doping Agency, were released after falling into the hands of Russian hackers. The records revealed Venus suffered from the immune system disorder, which can be characterized by dry eyes and dry mouth.

But the inspiration did not stop there. King also has been impressed with Williams being able to compete at her age.

“She’s winning huge and she’s 37,” she said.

For King, it is very important for the future of American tennis to have American players winning.

“It would really help U.S. Tennis if we could get some Americans winning the U.S. Open, for instance,” King said. “We need that. In the old days [Americans] were the winners, we were the number ones, we were the ones that made the game grow in the 70s.”

According to King, the first step to a resurgence in American tennis is to “get critical masses playing. And out of that, hopefully get some future champions, which we need desperately.”

Young American players had better start to pick up the slack soon because, as King said, “once Venus and Serena are gone, we’re not winning.”

In recent years, American women’s tennis has started to take notice of younger talents such as Madison Keys (22) and CiCi Bellis (18). However the U.S. is still far from the level of greatness it held back in the 1970s. The highest-ranked American men’s tennis player today is Jack Sock with the 17th spot, according to ATP Rankings.