(RNN) - Kim Clijsters is a four-time Grand Slam singles champion and won two more in doubles, so she doesn't need the advice of a fan. But that doesn't mean she can't have a little fun with one. Clijsters asked her partner where she should serve during the Wimbledon ladies' invitational doubles. A fan answered and Clijsters suggested he stand in to receive the serve. The invitational doubles are not as serious a competition as other Wimbledon events, and the matches take on a light-hearted tone. However, the strict dress code at Wimbledon rests for no one, so Clijsters brought the man a white skirt to cover up his blue shorts, which somehow managed to fit. Clijsters served to him twice, the first of which he successfully returned.