Fifa should reconsider the decision to play Women's 2015 World Cup matches on artificial pitches, according to former England captain Faye White.
As Canada prepares to host next year's tournament, 40 top players have signed a petition and threatened legal action if matches are not played on grass.
White told BBC Sport: "Fifa would never dream of hosting a men's World Cup on artificial pitches so why the women's?
"It makes you wonder if the women are some kind of guinea pigs."
The petition has been signed by the 2012 and 2013 Fifa Players of the Year, Abby Wambach of the United States and Germany's Nadine Angerer, as well as White and England international Anita Asante.
A legal letter has been sent to world governing body Fifa and the Women's World Cup organisers in Canada accusing them of discrimination.
It says: "Singling out this women's tournament for sub-standard treatment is a mistake that can and must be corrected."
A Fifa spokesman said the organisation had no comment to make about the letter it had received, but did tell the BBC that the Canadian Soccer Association and its National Organising Committee had proposed to use artificial turf at the tournament, which had been approved.
White, who retired in 2012 after playing 90 times for England, added: "It's a strange decision. I've retired from playing now but I would be really annoyed if I was expected to play on this.
"These pitches slow the game down, the ball bounces differently and there are more injury consequences.
"I can't believe there aren't enough grass pitches to host World Cup games in Canada. You've got to question why Fifa awarded it to Canada in the first place if that was the case."
|Women's World Cup Qualifying Group Six|
The 24-team World Cup starts on 6 June and will be held across six cities, with the final scheduled for Vancouver's BC Place Stadium on 5 July.
England, Wales and Scotland are aiming to qualify. England top their qualifying group and need one point from their final two games, with second-placed Wales their next opponents on 21 August.
Scotland are joint-top with Sweden in their group although the Swedes have played one game fewer.
The winners of the seven European groups automatically qualify, with the best four runners-up facing each other in play-offs for the final berth.