Los Angeles (AFP) - Seven hard-court tournaments that lead up to the US Open will join the Grand Slam event in adding "shot-clocks" to monitor time between points and the time of warm-ups.
The US Tennis Association, ATP and WTA announced the changes on Wednesday, saying tournaments in Washington, San Jose, California, Montreal, Toronto, Cincinnati, New Haven, Connecticut, and Winston-Salem, North Carolina would all use the 25-second serve clocks and enforce a strict seven-minute warm-up period.
The USTA had announced in April that the serve clock would be used at the final Grand Slam of the year.
Wednesday's announcement comes days after world number one Rafael Nadal blasted plans to introduce a 25-second shot clock at Wimbledon next year.
Routinely warned for slow play between points, Nadal said he believes players need time to compose themselves between points and to ponder tactics over five sets.
"If you want to see a quick game without thinking, well done," he said of the plan."
The serve clock to be used in North America this year will allow the server 25 seconds to serve, with players receiving a time violation from the chair umpire if they take too long.
The clock will be visible on court and the chair umpire will have the discretion to pause the clock.
Serbia's 12-time Grand Slam champion Novak Djokovic isn't a fan of the shot-clock idea.
"I don't like the shot clocks between the points," Djokovic said after reaching the Wimbledon semi-finals with a victory over Kei Nishikori on Wednesday.
"It's something the US Open is going to introduce this year without consulting players. That's really not nice and not fair. But it is what it is. You have to accept it and deal with it."
Djokovic, who was handed a time violation at Wimbledon on Wednesday in his win over Nishikori for taking too long to serve, thought the warm-up clock might be useful.
Players will have one minute from arriving at their chairs to get to the net for the coin toss and then five minutes to warm up, with a further minute allotted from the end of warmup to the start of play.
Those who go over will face fines.
"I think it's good to have maybe a shot clock for the warmup, the walk into the court," Djokovic said. "Obviously you don't want players to take too much time when they walk into court and sit down and drink, they just walked in. You want to get on with the warmup.
"But at the same time there should be always a little bit of, I guess, a tolerance and understanding of the game, of the pace of the match, how it goes," Djokovic added.