Victoria Azarenka retires from first-round match at French Open with injury

Victoria Azarenka was forced to retire from her first-round match against Karin Knapp at the French Open with a knee injury on Monday.

The Belarusian, who reached the semi-final of the Grand Slam in Paris three years ago, struggled throughout the clash before pulling out four games into the third set with the tie at 3-6 7-6(6) 0-4 in Paris.

Azarenka started strongly in the first set by going an early break up, but Knapp earned a double break before taking the lead on the clay court.

The two-time Australian Open champion battled back in the second set by breaking serve three times, but Knapp matched her opponent all the way.

A tie-break was needed to separate the two, and it was Azarenka who edged it 8-6 to force the match into a third and deciding set.

The set lasted just 20 minutes, though, with Knapp leading 4-0 when Azarenka withdrew from the match.