Stan Wawrinka believes Rafael Nadal should not be allowed to ban Carlos Bernardes from umpiring his matches, and has called for timing rules to be applied evenly across the ATP Tour.
Nadal made the request after receiving a series of time violations from the Brazilian official in relation to his slow play and routine before serving.
Wawrinka does not believe Nadal should be allowed to specify who can and cannot officiate his matches, and would like to see more players penalised if they fall foul of the law.
"When a player makes such a request it should be granted only if the umpire has made mistakes or faults," he said after his second-round win over Dusan Lajovic at the French Open.
"If it's just because he doesn't like the person, this request should not be accepted.
"I am not aware of Rafa's motivations, but I have read a few articles that it would be about pressure this particular umpire put on him due to timing.
"[I think] you need to be more strict about the 25 seconds, umpires don't always keep the same watch for all players because they know if they have trouble with one of the top players they can't be on their match.
"It then becomes tough for them because they like being there for the finals and if they have problems with top players it becomes difficult for them.
"So that's the problem we have on Tour with regards to a couple of rules, but umpires are not as strict on the centre courts when they are with the top players as compared as to when they on court number 17 [an outside court]."