Venus Williams joined retired soccer star Julie Foudy and ice hockey player Hilary Knight in the Eiffel Tower to highlight the push for pay equality for women athletes.

Williams, a five-time Wimbledon and two-time U.S. Open champion, got involved in the women's player council 20 years ago, when she was 18. While the U.S. Open reached pay equality in 1973 after Billie Jean King threatened a boycott, the Australian Open didn't follow until 2001, the French Open in 2006 and Wimbledon in 2007.

Williams praised women athletes who had joined the push for better pay and conditions.

"Not everyone wants to get on the train," she said. "So if they don't want to go to glory and go to the top of the mountain, they can stay at the base camp."

Players on the U.S soccer team sued the U.S. Soccer Federation (USSF) in March, charging institutionalized gender discrimination. The USSF countered that pay and benefits for members of the men's and women's teams, bargained by separate unions, can't be compared and said there was no basis for allegations of illegal conduct.

Foudy, a 48-year-old former midfielder who won two World Cups and two Olympics, recited poor conditions for her and teammates in the 1990s, recalling they were "staying in roach motels and driving the hotel shuttle bus to games."

"We actually won a World Cup in 1991, yet at that time, there was no marketing, there was no support for the team, we were getting 10 U.S. dollars a day," she said.

FIFA doubled the prize money for the women to 30 million U.S. dollars this year from the amount four years ago, and the amount for the winning team is four million U.S. dollars. That remains a fraction of the money awarded at last year's men's World Cup, where France received 38 million from a 400 million U.S. dollars pool. FIFA has raised the men's pool to 440 million U.S. dollars for 2022.

Knight, a 29-year-old ice hockey forward, won an Olympic gold medal last year after silvers in 2010 and 2014. She was among 200 women who announced in May they will not play professional hockey in North America this year in an attempt to establish a single, economically viable professional league.