An unnamed Russian player was stopped by Czech police from entering the country to compete in the WTA Prague Open.
A new government resolution has banned athletes from Russia or Belarus taking part in any events in the Czech Republic.
Several Russian and Belarusian players had been expected to compete in Prague as neutrals.
But tournament organisers have now told them not to travel.
Tournament director Miroslav Maly said: “She was the first participant to arrive to the Czech Republic with a Russian passport.
“The management of the tournament fully respect the current stance of state authorities. We do not expect any player with Russian or Belarusian citizenship to take part in the tournament in this situation.”
Last week, Russia’s Vera Zvonareva was blocked from entering Poland for the Warsaw Open “for reasons of state security and public safety”.
The decisions come as a result of Russia’s continuing invasion of Ukraine.