Movements which were once as natural as flying is to a bird are now off limits. There will be no lunging towards tramlines, or stretching every sinew to serve at speed. The grand slam champion has to begin from the very beginning. She is starting from zero.
She attempts to hit the ball in quick succession, but her heart rate bursts to 180 beats per minute. A no-go zone for the new mum. A gentle two-shot rally with her coach is her maximum.
Clijsters’ return to professional tennis will be measured, calculated. Progress will be made at a crawl.
For a 27-year-old woman who has already been world No.1, life will, sometimes, be frustrating, but there is no fast-track to sporting success, even for a talent such as Clijsters.
It will be another seven months before she is ready to play competitively, to challenge herself against her peers.
Serena Williams has all of this to come
One of the greatest athletes of her generation is expecting her first child and fresh challenges, a new perspective, are before her.
Williams has said she will make her tennis comeback next year, but will a 35-year-old who has won it all really return to the sport in which she made her name?
Wim Fissette, Clijsters’ former coach, believes we have seen the last of Williams at grand slams, dazzling with her flawless serve, overpowering opponents with her destructive groundstrokes.