PARIS (Reuters) - Roger Federer has given warning that players taking their mobile phones on to court could undermine the game's integrity by receiving coaching tips.
The French Open has already featured two incidents with Ukraine's Sergiy Stakhovsky using his phone to take a picture of a ball imprint after a contentious line call and local favourite Gael Monfils snapping a Mexican wave in the crowd.
Stakhovsky, who was later fined $2,000 for unsportsmanlike conduct, posted the picture taken during his first-round defeat by Richard Gasquet on his Twitter feed.
Federer, the world number three and seeded second in Paris, said he could see the funny side of such incidents but felt action might be needed to prevent on-court coaching.
"It's only going to happen more," the world number three told reporters. "I think it's pretty funny, actually. The problem is that clearly there could be coaching going on through mobile devices.
"It would probably be so easy to do. Go to the toilet and you hide it somewhere - I'm just saying anything is possible. You have to hope that the players use it in a funny way and it's not meant to be bad or disrespectful."
The use of phones on court is prohibited with officials instructed that no electronic device be permitted "during matches unless approved by the ITF supervisor/referee".
If officials suspect a player has used a device to receive coaching, they could issue a fine of up to $20,000.
Monfils escaped punishment because he asked the umpire for permission to take a picture of the crowd who had risen to salute him during his second-round victory over Ernests Gulbis.
"I asked the chair umpire before if I would be allowed to tape the wave? He told me: 'Sure, you can'," said the Frenchman.
Grand Slam Committee director Bill Babcock told Reuters by email that the subject "will certainly be raised" as part of the ongoing review of the rules and code of conduct.
"Although the current rule is conclusive in that players are not allowed to use devices at all unless approved, we can and should always consider ways to make sure the rule is consistently enforced," he said.
Editing by Tony Goodson and John Mehaffey