Rafael Nadal was left angered with his Davis Cup semi-final coming so soon after his US Open final appearance.
The 25-year-old lost to Novak Djokovic at Flushing Meadows last Monday night and was in Spain on Friday representing his country against France.
"It is unacceptable that two big events like a Grand Slam and a Davis Cup semi-final are so close," he said after his straight-sets victory over Richard Gasquet.
"I wouldn't like to go as far as a strike because playing is what I like to do. But something has to happen.
"As the International Tennis Federation doesn't want to listen, it would seem that the only way to get things moving is to act in the strongest manner."
Nadal had led the protests at the US Open after a series of rain delays caused scheduling chaos.
