The tennis 'shot clock' is finding unlikely favor with players known for taking longer between points, helping them stay within the rules and even providing a few extra seconds.
The clock is being used at ATP and WTA events across Washington, Toronto, Montreal and Cincinnati, following the US Open's decision to introduce it in regular competition.
"I think it's good," said Marin Čilić, who tends to take quite a bit of time before starting his serving motion. "It's what we needed in the game. It has been so much talked about, and I feel also for the referees, the responsibility is taken from them.
"Some referees [were] enforcing the rule, some are very lenient. It's not very consistent."
The change has attempted to balance greater consistency with flexibility. While tennis rules call for players to take a maximum of 25 seconds between points, the shot clock begins when the umpire calls the score, allowing officials to allow for long points or crowd excitement. Umpires can also pause the clock in other instances.