As bald patches surface,the game changes

So do groundskeepers,who realize that not much can be done to improve a court8217;s appearance by this stage of the tournament. As long as players prefer slugging out points with ground strokes,the baseline will remain the most heavily trafficked area of the court.

Asked why his forehand started working better in the third set of his loss to Andy Murray on Friday,Jo-Wilfried Tsonga said: When you have the ball above the net height on grass,it8217;s easier to play,and when the ball comes at you more slowly,it8217;s easier to play. But when a guy hits hard and deep,I think you have to have been out there playing to understand,but it8217;s hard to really hit the ball. You can8217;t really hit on grass. There are lots of bad bounces,so when the guy plays deep into the spot where the grass has been worn down and he doesn8217;t leave you the time to play,you don8217;t have time to play fast yourself.

The best that groundskeepers can do is patrol those bare areas with a high-powered vacuum called a Billy Goat,which slurps up lingering dust and debris.

Mark Ferguson is one of three members of the Sports Turf Research Institute8217;s on-site team,which monitors the performance and the playing quality of the courts. The wear and tear sustained at Wimbledon in two weeks,he said,was not unlike what a soccer field experiences 8211; over a full season.

Those patches can produce irregular bounces 8211; obvious to the player,but barely perceptible to fans in the crowd or television viewers. If the ball strikes a bare spot,it is more likely to decelerate or bounce slightly higher than it is to skid laterally.

On the whole,the surface plays much more like a hard court than it did 15 years ago. The grass then was laden with poa annua,a weed also known as bluegrass,and rewarded players whose fast serves would skid along the soft court. It was so spongy,in fact,that Patrick McEnroe said he changed his ritual before serving because the ball would not bounce back into his hand.

Vital switch

In consultation with the Sports Turf Research Institute,Wimbledon in 2001 switched to a perennial ryegrass,which yields higher bounces. Underneath that ryegrass is a clay-based,loamy-type of soil that,when it dries out and the grass above is ripped away,can generate cracks.

McEnroe cited Rafael Nadal8217;s early round struggles at Wimbledon. Even though Nadal has won two titles here en route to a 36-6 record,it often takes him a few matches to find a rhythm. Of the eight five-set matches he has played at Wimbledon,five have come within the first week,when the grass is softer. Without solid footing,Nadal cannot generate as much racket speed to lash his ground strokes,which hindered him during a second-round loss to Lukas Rosol.