Former tennis champ Kim Clijsters has added a boy to her brood after giving birth on Wednesday (18Sep13).

The Belgian sports star took to just hours after the birth to tell fans of little Jack's arrival.

She writes, "Jack Leon Lynch is born! Born at 7.06 pm tonight and we are both doing well... His big sister, mama and daddy are very proud and happy!"

The tot is a little brother to five-year-old Jada Ellie, Clijsters first child with her husband Brian Lynch.

The 30 year old retired from the court following the U.S. Open last year (12).