So much so that before Alisa Kleybanova went on court and was ground down by the Dane in a three-setter in Tuesday’s fourth round at the BNP Paribas Open, she noted how some players already are lacking confidence before they go on court against Wozniacki because she puts up such a wall behind the baseline that they don’t know how to hit through or around her. Some get so discouraged that they mentally throw in the towel before they strike the first ball.