Benedict Cumberbatch is used to working with big names, but even he was impressed by the cast of a new project.
With the help of Count von Count (Matt Vogel) and Murray Monster (Joseph Mazzarino), Cumberbatch explains how to count up four apples and three oranges, and which is the greater number.
He also, patiently and repeatedly, tries to get a skeptical Murray to believe that he is not actually Sherlock Holmes but just plays the detective on TV.
Cumberbatch taped the spot in January, when he joined actress Amanda Abbington to promote the new Sherlock season to a TV critics meeting in Pasadena, California. His puppet encounter proved to be something to brag about.
"I just met with the Muppets," Cumberbatch gleefully told Abbington, who plays the wife of Dr Watson (Martin Freeman, her real-life partner).
"Did you have a good time?" she asked.
"It was so much fun," he said, adding, "They are real."
They are, agreed a smiling Abbington.