Belgian tennis players Yanina Wickmayer and Xavier Malisse have appealed to Switzerland's Supreme Court to end a two-year investigation into whether they broke anti-doping rules.
The Court of Arbitration for Sport says the players have asked the Swiss Federal Tribunal to rule that CAS has no authority to judge them.
CAS says its scheduled Sept. 12 hearing involving Wickmayer, Malisse and the World Anti-Doping Agency has therefore been suspended.
Wickmayer, currently ranked No. 21, and 54th-ranked Malisse got one-year bans in 2009 after a Belgian doping tribunal ruled they failed to give details of their whereabouts for drug testing.
They returned to play after a different Belgian court granted injunctions against the bans.