From the SI website, they compiled some quotes from players autobiographies :
Passing Shots: Pam Shriver on Tour, by Pam Shriver, Frank Deford and Susan Adams
Page 127: "I'm lucky I played Steffi Graf on grass. It's her worst surface, and she didn't serve and volley at all. Today Mr. Graf was sitting right behind the linesman, and when he called one of Steffi's passing shots out, Mr. Graf started yelling 'No, no, no' right in the poor guy's ear. So I turned to him and yelled, 'Shut up!' and he did. There wasn't a peep out of him the rest of the match."