Princess Eugenie was mortified when Beyonce pulled her up on stage to perform a duet at the O2 arena last night (30.04.13).
However, Eugenie - the daughter of the Duke and Duchess of York and sixth in line to the throne - succumbed to the pressure of performing in front of 80,000 people and failed to join in on Beyonce's hit single Irreplaceable.
When the 31-year-old singer handed her the microphone and asked her to repeat, "To the left, to the left", Eugenie, 23, was unable to make a sound.
A source told the Daily Mirror: "It was hilarious - Eugenie was on the front row with Kate Middleton's brother, James, and his new girlfriend, Donna Air, plus designers Matthew Williamson and Patrick Cox.
"Beyonce clearly didn't recognise her so when it came to Irreplaceable, and the part where she picks on an audience member to join in with her, she simply chose the first woman she could reach.
"When Eugenie, who had gone bright red, ducked down, Beyonce was forced to quickly fill in the missing words and find a new, willing victim.
"All Eugenie's friends were teasing her about her stage fright for hours afterwards."
Meanwhile, the princess' sister Beatrice was spotted dining at Bodo's Schloss restaurant in South Kensington with Glee star Matthew Morrison.
Tickets for Beyonce's upcoming concerts at the O2 here.