Perth - Serena Williams' Australian Open
title defence is under a major injury cloud after she retired from her singles
match against Australia Jarmila Wolfe at the Hopman Cup on Tuesday evening in
The world number one and winner of 21 Grand
Slams will be aiming for a seventh singles title in Melbourne later this month,
but is being troubled by a nagging left knee injury and retired when trailing
The problem sidelined her for much of the
latter part of 2015 and she withdrew from the United States' opening Hopman Cup
tie on Monday, citing inflammation of the left knee after a practice session.
Williams trained again briefly on Tuesday
and took to the court against Wolfe (nee Gajdosova), but appeared very
restricted in her movements especially on her left side.
The 34-year-old served for the first set,
but was broken by Wolfe, who then took the set 7-5.
When Wolfe broke her again for a 2-1 lead
in the second set, Williams called for the trainer and after a brief discussion
Williams' coach Patrick Mouratoglou
conceded in November that her knees were troubling her.
She did not play for two months after her
calendar Grand Slam hopes were derailed by Italian Roberta Vinci in the US Open
semi-finals in September.
Williams returned in the International
Premier Tennis League in Manila last month.