Princess Beatrice accidentally cut singer Ed Sheeran's face with a sword during a party prank which involved her pretending to "knight" James Blunt, according to reports.
The Sun said that Ed, 25, went to hospital to have stitches on his cheek after Beatrice, 28, accidentally swung the ceremonial blade over her shoulder, not realising that the Thinking Out Loud singer was behind her.
The incident is reported to have happened at a party at the Royal Lodge in Windsor, after You're Beautiful singer James, 42, joked that he would love to be made a Sir.
The newspaper said that while Prince Andrew was away on business, Beatrice's mother Sarah Ferguson was at the do.
A source was quoted as saying that there were around 20 guests at the party.
"Apparently, James Blunt joked that he would love a knighthood," the source said.
"Beatrice jokingly said she could arrange it and fetched a ceremonial sword... James played along with the prank and got down on one knee as he would if he were at Buckingham Palace being honoured by the Queen.
"Beatrice, who was in great form, held the sword above him and said 'arise Sir James',... But she must have misjudged the weight or something and, instead of lightly tapping him on the shoulder, she swung it back, not knowing Ed was standing right behind her.
"The blade cut into his face and it was just a few inches from his right eye."
Ed, who has been pictured with the cut and is taking a break from the music industry, apparently returned to the party, which he is said to have attended with his girlfriend, Cherry Seaborn, after leaving hospital.
A Buckingham Palace spokeswoman said that there was no comment.
A spokeswoman for James declined to comment.
Ed's publicist has been contacted for comment.