Originally Posted by Moose Malloy
In Open, Agassi also described a 'tell' Todd Martin had. If he looked for long time at a particular spot just before serving he would end up serving in the opposite direction. If he just glanced at a particular spot before serving, he would hit it there.
I guess these little things are just another form of expressiveness. I mean how tennis players mention all the time how they try not to give the opponent anything they can use -- try not to show what they're thinking or feeling, oncourt or off. Express yourself in any way, and someone shrewd can exploit it.