Former world number one Tracy Austin says the Women's Tennis Association must act to avoid the spiralling number of injuries affecting its top players.
Sharapova suffered both back and chest injuries in 2005
Maria Sharapova, Lindsay Davenport, Justine Henin-Hardenne and the Williams sisters spent long periods out in 2005.
"It's not a coincidence there are this many injuries," Austin told BBC Sport.
"If the WTA and (their chief executive) Larry Scott don't take this as a big warning that something needs to be done, then they have got a problem."
Austin, a winner of two US Open titles, had her own career cut short at the age of 21 by chronic injuries.
She told BBC Sport that the women's game would be left in crisis if the WTA refused to make dramatic changes to its schedule.
THE SIDELINED STARS
Serena Williams: ankle and knee injuries, played just 28 games in '05
Maria Sharapova: back injury all summer, then pectoral problems
Lindsay Davenport: back injury
Kim Clijsters: wrist and knee injuries, will quit tennis in '07
Justine Henin-Hardenne: knee and hamstring injuries all year
Martina Hingis: retired aged 22 with chronic ankle injuries
Jennifer Capriati: missed whole of '05 with shoulder injury
"The players are crying out for the season to be shorter," she said.
"During the summer hard-court season, Kim Clijsters played four weeks in a row and really saved some of the tournaments.
"But some of the tournaments still didn't do as well as they should because a lot of the top players were injured.
"The WTA needs to shorten the season, because the biggest factor in the injuries is over-use.
"In American football, the entire season is just four months long.
"In tennis, we're talking just six weeks off all year. And during those, you've got only two weeks you can take off completely, to physically and mentally recharge.
"Then you've got to charge up again because the Australian Open and the start of the season is just around the corner.
"I just don't think two weeks off like that is enough."
No career longevity
Mark Bender, former physio to the Great Britain Davis Cup team, echoed Austin's criticisms.
"It's a very sad issue and it's going to keep happening," he told BBC Sport.
"I don't think you will see players any more with the career longevity of, say, Martina Navratilova or Chris Evert."
The official WTA line is that the current spate of injuries is down to nothing but chance.
CEO Larry Scott said: "Injuries are a part of every sport. It is a bit of a fluke that so many players are injured at the same time, and I don't expect this to happen next summer."
But Navratilova, who has played over 2,300 games on the WTA tour to date, is also demanding action from the tour.
She said: "We should have had an off-season long ago, even before injuries became such a big part of the game.
"It's not acceptable to have so many top players not being able to get well and stay well."
Austin said that the WTA had made a rod for its own back by guaranteeing too many tournament organisers a slice of the pie.
"Amelie Mauresmo gave herself a self-imposed two weeks off after Wimbledon this year.
"The tour called and said, 'Hey - we need you because of all the injuries to other players', and she said, 'no, this is my time I've taken off'.
"But the problem is, whose tournaments are you going to take off?
"I don't know if the WTA has enough money to buy a couple of weeks.
"Moscow are not going to give their week up, or Filderstadt, and so on and so on. They've already sold the tour with this many weeks."