"Kim Clijsters and Brian Lynch were married by mayor Jack Gabriels in the strictest privacy, in the presence of just both their families," town official Lidia Seerra told AFP.

"There were few people, but the parents of the young couple were present."

Clijsters' sister Elke and Brian's brother acted as witnesses.

The civil ceremony had been scheduled for Thursday evening but the mayor, fearing an influx of excited fans, announced that it was being postponed without saying when it would take place.

The 24-year-old Clijsters, who revealed on her website that she is expecting a baby, has been living with Lynch for the past two years. Lynch plays for the basketball team in Bree.

The couple plan to spend some time in the United States after the wedding.

The Belgian ace, who won 34 WTA singles titles in her career including the US Open in 2005, said that battling injuries and the constant effort to stay at the top had finally taken their toll and it was time to hang up her racket.

She retired from competition in May.