Tennis players taking part in private tournaments while the sport is in lockdown have been warned that match-fixers remain a threat.
ATP and WTA events have been on ice for over a month and will not resume until 13 July at the earliest.
In the meantime, exhibition matches, as well as virtual tennis tournaments, have been suggested as a means to sharpen competitive edges and boost bank balances.
"The suspension of professional tennis is an uncertain and challenging time for the tennis community," said a statement from corruption watchdog, the Tennis Integrity Unit.
"Some privately organised exhibition matches, tournaments and even eSports events will start to take place where and when local government restrictions allow.
"We understand that these will be attractive opportunities to many of you eager to play and to earn an income.
"While the playing opportunities created are welcomed, we must advise you that there may be an elevated risk of corruption and corrupt approaches in some of these environments."
Rafael Nadal and Patrick Mouratoglou, the coach of Serena Williams, both say that they plan events at their academies.
The Nadal Academy in Mallorca said it was considering becoming "a campus where elite players can reside, train and compete between themselves in matches that will be televised so that fans around the world can enjoy them."
Mouratoglou released a statement unveiling a planned "league" of 50 matches at his academy near Nice in the south of France and talking of "millions of US dollars in prize money".
Mouratoglou said he was planning 10 closed-door matches to be broadcast live on each of five weekends under the title "Ultimate Tennis Showdown".
The competition will start on the weekend of 16 May with a match between world No 10 David Goffin and 20-year-old Australian Alexei Popyrin.