Therefore , watching the ball throughout its entire flight is not the visual strategy used by elite players .
More broadly , Federer and Nadal demonstrate that it is possible and even beneficial to play tennis with the eyes not always focused on the ball .
Watching the ball throughout its entire flight is not the visual strategy used by elite players .
More broadly , Federer and Nadal demonstrate that it is possible and even beneficial to play tennis with the eyes not always focused on the ball .