Clijsters has twice been winner in Indian Wells - now officially the BNP Paribas Open - in 2003 and 2005, but last week did not go as planned for the Flemish star: she had to retire, injured, from her fourth round match in the middle of the second set, handing victory to France's Marion Bartoli. In fact, Clijsters had complained of shoulder problems all week and had been getting regular treatments for the injury, but it all caught up to her against Bartoli.

This might be simply a routine setback for Clijsters; all athletes face injury at some point. But the Indian Wells injury seemed more like a question of age catching up with the 27-year-old and a reminder that she won't be strutting on the tennis stage for that much longer. Indeed, Clijsters already said she planned to retire after the 2012 London Olympics, so her time limit is in some ways self-imposed.

Clijsters is one of the most popular tennis stars of recent years and has already retired once, in 2007. That preceded an extraordinary turnaround: after marrying and having a daughter, she returned to the game two years ago. Her comeback performance surpassed her first career: retiring with just one major, the US Open, to her name, she has since notched two more and - just this January - the Australian title. After Australia, she was briefly number one in the world rankings - the first time ever for a mother.

Clijsters has been taking painkillers since January to cope with the shoulder injury. "I still felt I could have won," she said after the match. "I could have taken painkillers, but I don't want to risk tearing it, and I don't want to be in a situation where I am taking medication to cover something up. It makes me realise I am not the youngest out there, and maybe I don't recover as fast."

Maybe this is just usual wear and tear, Clijsters will recover, and even reconsider her 2012 retirement plans. But it also suggests that she is human after all, and tennis fans should savour her remaining moments on the court.

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