Russian and Belarusian players fear they could miss Wimbledon because they are still waiting for UK visas.
The All England Club banned them from competing last year following Russia’s invasion of Ukraine, which was supported by Belarus.
They can compete this year but must sign declarations indicating their neutrality.
The Home Office said applicants have to undergo “thorough checks” before permission to enter the UK is granted.
Wimbledon takes place in London from 3-16 July.
Sixteen-year-old Russian Mirra Andreeva, who had impressive runs at the Madrid Open and the French Open, said she is still waiting to see if she can play at the tournament.
Andreeva applied for her visa more than six weeks ago and it has still not been approved.
Speaking on Saturday, Andreeva – who could be a candidate for a wildcard based on her performance in Paris – said: “Now I’m limited still in tournaments, so my next tournament has to be Wimbledon.
“But I don’t get my visa yet, so we will see if I can participate in Wimbledon or not.”
Following Russia’s invasion of Ukraine in February 2022, the UK government put in place a set of sanctions against the nation and its citizens.
It includes visa-related measures, which includes reducing appointment capacity and more stringent checks for anyone applying.
“We treat each application on a case-by-case basis and all applications to enter the UK will be assessed on their merit,” a Home Office spokesperson said.
“Applicants will have to submit their biometrics and undergo thorough checks before permission to enter the UK is granted.”
The government website states it takes three weeks to process an international sportsperson visa, but it can take longer.
Russian world number 11 Karen Khachanov said “it takes [a] much longer time to issue the documents”, but added he already had a valid visa from previous years.
After losing in the first round at Roland Garros, men’s world number two Daniil Medvedev indicated he had doubts about his participation at Wimbledon by saying he would be “happy” if he was “able to come to the UK” for the grass-court Grand Slam.
Belarusian women’s world number two Aryna Sabalenka, who again did not do an open news conference after reaching the French Open quarter-finals, said in May she had not yet had her visa approved.
Russian player Anastasia Pavlyuchenkova, who is through to the last eight at Roland Garros, is set to miss the tournament as her current world ranking of 333rd is not high enough to enter the main draw or qualifying.
On her chances of a wildcard after her run in Paris, she said: “Are you serious? Do you think after the situation last year they would give me a wildcard this year?”
Russian and Belarusian players have competed as neutral athletes on the ATP and WTA Tours since the invasion began.
As part of the conditions of playing at Wimbledon, players must agree not to support the Russian and Belarusian states or their regimes and leaders.
They must also not receive funding from Russian or Belarusian states, including sponsorship from companies operated or controlled by them.
