LONDON—Former player Javier Sanchez, who owns GreensSet, the company that laid down the courts in Basel, Paris, and the ATP World Tour Finals, says there is no difference in the speed of the surfaces. Some players claim the London court is slower than the one in Paris; some say London is faster; others say the surface speed seems the same as Paris.

“The courts are exactly same: The same speed, the same material, same guy who builds them,” Sanchez told TENNIS.com. “It could the perception of the players [that the speed is different] because this arena is bigger than Paris, so your feeling is different. The only difference between [London] and Paris is that Paris is built on wood underneath, because normally it’s an ice hockey arena so they have to fill the hole to make it level with the concrete, and here it is just on concrete. In Basel it's just on concrete.

"But in the [O2] arena which is bigger, when you see the ball, and you have Nadal, maybe he’s a half meter back and has a little but more time to see the ball and that little thing for him is a lot. Two milliseconds for him is a lot. Maybe it’s just a perception.”

The balls used in Basel, Paris and London are also said to be the same.

“But maybe humidity [in the O2] affects the ball,” Sanchez added. “If the ball is bigger it will affect the speed, but I don't know if that's happening. But normally it’s not that different. But for the players, a little can be a lot.”