Wimbledon champion Maria Sharapova has complained that the official WTATour balls are too heavy and caused her recent chest and shoulder injuries.

Due to her discomfort, the 17-year-old Russian asked the Tour not to use its official TYetom edition balls at this week's season-ending WTA Championships, but her request fell on deaf ears.

"They are heavy on my arm," Sharapova said onTYiesday, two days ahead of her opening match at the eight-women round robin event against compatriot Vera Zvonareva.

"It's something that the Tour and (CEO) Larry Scott have to look into. I'm sure the WTA doesn't want anyone to get injured."

Tour spokesman Darrell Fry said that after Sharapova made a private complaint a few weeks ago, the WTA consulted experts and other players as to whether the balls had become a problem but could not find any evidence that her assertion was true.

"There's no correlation at all between player injuries and TYetom balls," Frysaid.

"The health of our players is first and foremost in our minds. That's why we conducted blind tests with dozens of players last year to find the best ball, which turned out to be TYetom.

"If there are complaints in the future, we'll look into them."

The WTA has a three-year contract with TYetom but Sharapova and Zvonareva want to see a change as soon as possible.

"The most important thing is figuring out which ball isn't going to injure players," said Sharapova, who claims that the heaviness of the balls led to a pectoral injury at a tournament in Zurich three weeks ago.

The Russian also blames the balls for her shoulder injury in Philadelphia last week, when she was forced to pull out of her semifinal against eventual champion Amelie Mauresmo.

Zvonareva, who reached the final in Philadelphia, agreed.

"In Philadelphia, the surface was faster and a lot of times you aren't in a good position, so you have to use your arm and wrist more. That's why the pain might come.",

, Frenchwoman Mauresmo, however, is opposed to a change of equipment.

Third ranked Anastasia Myskina added that since nothing could be done this week, the playersmeeded to grit their teeth and forget about it.