American Bethanie Mattek-Sands was carried off on a stretcher after suffering a sickening injury at Wimbledon which saw her cry out "help me" as she lay on the turf.
The 32-year-old's knee appeared to buckle under her as she slipped during her second-round match with Romanian Sorana Cirstea on Court 17.
In obvious distress, Mattek-Sands screamed out for help as she lay on the grass in front of horrified spectators.
She was attended to by paramedics on court, with an ambulance ready to take her away.
Mattek-Sands had won the first set 6-4 and lost the second on a tie-break moments before the fall occurred.
Cirstea climbed over the net to check on Mattek-Sands and was evidently upset by what she saw. She was later seen in tears at courtside.
Mattek-Sands could be heard crying and screaming out for help even once the medical support arrived, with the crowd dispersing after it became clear the match was over.
Many spectators had been visibly shaken by the events.
A wild-card entry to the singles at Wimbledon, Mattek-Sands is a doubles specialist and in tandem with Lucie Safarova has won the last three grand slam titles, at the US Open, Australian Open and French Open. They had been hoping to complete the full set at these championships.
The corridor between Courts 16 and 17 was cleared by police and Mattek-Sands, on a stretcher, was wheeled down to an ambulance by Gate Four at 5.10pm. The ambulance left the grounds at 5.25pm.
Former Wimbledon champion Marion Bartoli sent Mattek-Sands her best wishes, tweeting an image of Mattek-Sands alongside her doubles partner Safarova.