Kim Clijsters Welcomes Baby Number 2

Tennis star Kim Clijsters and husband Brian Lynch welcomed their second baby, Jack Leon Lynch, Wednesday

"Jack Leon Lynch is born! Born at 7:06 p.m. tonight and we are both doing well," 30-year-old Kim announced on Twitter. "His big sister, mama and daddy are very proud and happy!" She gave birth in Belgium.

The couple's first child, Jada Ellie, will be elder sister to Jack. After Jada's birth, the tennis great returned to the game to win three more Grand Slam singles titles - the U.S. Open in 2009 and 2010 and the Australian Open in 2011 and returned to the top of the world rankings.

"We are of course delighted. I'm doing fine, even though I tire more easily right now," she wrote on her website following the birth.

Clijsters announced her retirement in 2007 to start a family with husband Lynch but was soon back in the game. Soon after the birth of their daughter Jada Elle in 2008, Clijsters returned to tennis and won the three Grand Slam titles.

She also won the U.S. Open in 2005 and the French Open and Wimbledon in 2003.

Kim and Lynch married in a private ceremony on July 13, 2007, at the Bree City Hall. She was married by the mayor, with sister Elke, Lynch's brother Pat Lynch and other family members in attendance.