Serena Williams’ planned appearance at Wimbledon in women’s doubles with her sister Venus is in doubt after she suffers a knee injury. Multiple outlets report that Williams “tweaked” her right knee during her first-round singles match at Wimbledon against Australia’s Maya Joint. The match ends in a three-set defeat, and coverage notes it occurs on Centre Court on Tuesday evening. Sources also say this singles outing follows Williams’ long absence from singles competition, with her first singles match in several years, and that she is preparing to partner with Venus at Wimbledon for the first time since they previously won the tournament’s doubles title about a decade ago. Several reports state the knee problem may affect her ability to compete in the doubles event later this week, though none confirm a final decision. The injury and her fitness ahead of the doubles match remain the key focus as she assesses whether she can continue competing at the championships.