Australian Open: Facts on women's injuries

A list of women players, who have been struggling in the lead-up to the season's opening Grand Slam at Melbourne Park, starting on Monday.

Serena Williams battled knee problems in the latter half of 2015 and was forced out of the mixed-teams Hopman Cup in Perth this month with a similar issue.

Injuries and illness have hit women's preparations for the Australian Open with a string of top players pulling out of warm-up events.

Here is a list of who has been struggling in the lead-up to the season's opening Grand Slam at Melbourne Park, starting Monday:

Serena Williams (USA x1): The American star battled knee problems in the latter half of 2015 and was forced out of the mixed-teams Hopman Cup in Perth this month with a similar issue. She insisted this week her body was now "feeling great".

Simona Halep (ROM x2): The Romanian pocket-rocket has been suffering from an achilles injury that saw her pull out of the Brisbane International. But she opted to play the Sydney International this week and has made the semi-finals.

Garbine Muguruza (ESP x3): The fast-improving Spaniard called for the trainer early in the Brisbane International to have her left foot bandaged because of blisters. But her movement was hampered and she retired from the tournament.

Agnieszka Radwanska (POL x4): The hard-working Pole won the Shenzhen Open this month but five matches in a week forced her out of the Sydney International to rest a troubled leg.

Maria Sharapova (RUS x5): The 28-year-old withdrew from the Brisbane event without hitting a ball after hurting her forearm in practice. She declared in Melbourne this week that she was now healthy.

Petra Kvitova (CZE x6): Kvitova was unable to defend her Sydney title after succumbing to a gastrointestinal illness, which also plagued her in China the week before.

Angelique Kerber (GER x7): The German made the final in Brisbane, losing to Victoria Azarenka, but came down with a stomach bug at the Sydney International this week and pulled out.

Lucie Safarova (CZE x9): Safarova is skipping the opening Grand Slam of the year because of ongoing health problems linked to a bacterial infection that saw her hospitalised for a week last September.

Sloane Stephens (USA x26): Stephens won the ASB Classic in Auckland this month but then pulled out of this week's Hobart International citing illness.