Imagine this scenario unfolding in a few weeks' time: Andre Agassi vs. Roger Federer, U.S. Open final, fifth set, full house, match point. Agassi whips a shot past Federer and drops to his knees, celebrating a Grand Slam title in his last tournament as a pro. The crowd goes wild.

Because of the money and logistics involved, the system is being used only on one court at most events and will be used at two of 18 courts at the U.S. Open (at a cost of about $300,000 US).

``You have to be the same for everyone _ same rules,'' top-10 player Tommy Robredo said.

His loss to Juan Carlos Ferrero in the Cincinnati Masters semifinals Saturday ended on a challenged call. Instead of closing out the match with an outright winner, Ferrero had to wait while Robredo made the umpire check a ruling.
© The Canadian Press, 2007