BBC Sport - Serena Williams' hopes of playing alongside older sister Venus in the Wimbledon doubles look in doubt after she injured her knee in her singles comeback.
The pair, who are six-time doubles champions at the All England Club, are due to reunite on a Grand Slam court for the first time since 2022 on Friday.
However, 44-year-old Serena Williams might not be fit enough to play after her knee swelled up during her defeat by Australia's Maya Joint on Tuesday.
The 23-time Grand Slam singles champion did not speak to the media following the match, with Wimbledon organisers saying she was "not able to undertake" her duties.
"Serena tweaked her right knee at the end of the first set and was therefore excused from her media obligations by the Wimbledon and WTA medical teams," said Williams' agent Jill Smoller.
"She left site that night unaided and is doing everything she can to be ready for her doubles match later this week."
Missing the doubles would be a hugely-disappointing ending to Williams' highly-anticipated return to the All England Club.
The American superstar has been the centre of the attention in SW19 over the past few days, with a high level of intrigue about why she was coming back and how she would look on court.
Williams played what she thought would be the final match of her career at the 2022 US Open, but tellingly refused to use the word 'retirement' and instead said she was "evolving away" from tennis.
After 1,462 days away from Wimbledon, she stepped back on to Centre Court on Tuesday.
At the place where she won her seven singles and six women's doubles titles, Williams showed signs of her incomparable talent and could have earned a sensational win against 20-year-old Joint.
Joint held firm, though, to claim a 6-3 6-7 (6-8) 6-3 win.
However, Williams' fight and determination as she looked to satisfy an insatiable appetite to beat opponents - having famously said she hates losing more than she loves winning - may have come at a bitter cost.
