Copyright © 2015. No duplication is permitted without permission from Bob Larson Tennis.

Serena Williams’ coach and confidante Patrick Mouratoglou has revealed the world no.1’s tennis future currently hangs in the balance and she must reduce workload if she is to prolong her career.

Mouratoglou, in Paris at a function arranged by Maui Jim sunglasses for which he is an ambassador, dispelled the prevalent theory that Williams wanted to distance herself from tennis for the remainder of 2015 simply because she was distraught at failing in her ambition to complete the calendar Grand Slam at the US Open. Instead the 34 year-old’s knees are in such a chronic state they have nearly run out of cartilage.

As a result the current holder of the Australian Open, French Open and Wimbledon titles has been playing for the entire year under the threat of a career-ending stress fracture.

“The cartilage is not gone, not all of it, but a big part,” said Mouratoglou at the BNP Paribas Masters and Paris’ Palais de Omnisports Bercy. “She has bone bruises and if you keep on playing with this for too long, the next step is a stress fracture.

“At her age, her career could really be in danger if she went too far and got more injured like Rafa [Nadal] did in the past. He kept on playing with the same problem and then it got worse and he had to stop for almost a year. We don’t want this to happen. She is 34. If she has to stop for a year then it is really bad for her.”

Chronic knee pain could well have been a factor in William’s US Open semi-final defeat against Italy’s Roberta Vinci and Mouratoglou is convinced the world no.1 must completely rethink her schedule if she is to win one more Grand Slam title to equal Steffi Graf’s total of 22 and then add another three to surpass Margaret Court’s all time best of 24.

The Frenchman revealed: “The first thing she said when she came to the court, to warm up before the match against Vinci, was ‘My knees hurt so much today’.

“So she was really struggling to move. And I think also the tension went to another level. I take my responsibility on that because I couldn’t find a way to make her handle it better.”

Williams has won eight titles from 14 grand-slam tournaments entered since and she and Mouratoglou teamed up in the summer of 2012.

Copyright © 2015. No duplication is permitted without permission from Bob Larson Tennis.