Even princesses get tongue-tied around Beyonce. The American music superstar has reportedly unwittingly embarrassed Princess Eugenie when she picked the British royal to sing along with her at her London concert.

Beyonce was singing her 2006 chart-topping song “Irreplaceable” at the O2 arena in London when went to the audience at the front row to sing the catchy lyrics, “To the left, to the left,” along with her.

Fans who were chosen to sing the line happily did so, but one got nervous and just smiled. Beyonce pointed the mic to Princess Eugenie, expecting her to sing the lyrics, but the Princes William and Harry’s 23-year-old cousin seemingly froze up. Even her companions weren’t able to sing.

“It was hilarious – Eugene was on the front row with Kate Middleton’s brother, James, and his new girlfriend, Donna Air, plus designers Matthew Williamson and Patrick Cox,” a concert attendee told The Mirror.

“She was really excitable and filming the whole thing on her iPhone like any other fan. 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.”

According to a YouTube video shot by a fan, Eugenie didn’t duck when Beyonce got near them, although she did a little awkward dancing in front of the performer. It was a sight to behold, nonetheless, with the disputable queen of pop and the sixth in line to the British throne in one frame.

The incident can be seen around 1:15-mark.