Aida Garifullina is performing with Robbie (Picture: Getty Images)What TV channel is the opening ceremony on?
He said when his performance at the ceremony was announced on Monday that it was "a boyhood dream" and would be "an unforgettable show".
Why the 44-year-old chose to be a bit cheeky during his massive performance is now unknown, but several outlets report the gesture may have breached Russia's broadcast guidelines.
Russia, who are tournament's lowest-placed team at the 70th spot in the FIFA's World Rankings, are heading into the showpiece event in full strength, but they are yet to win a friendly in 2018.
With the controversial Video Assistant Referee (VAR) system making its World Cup debut, Italy's Massimiliano Irrati is the designated VAR official in Moscow.
Shaun Botterill via Getty Images Artists perform in the opening ceremony.
The ceremony oped with a pre-recorded segment, filmed outside and overhead the stadium.
Standing on a giant half-football in the middle of the Luzhniki Stadium, dressed in a burgundy leopard skin suit and surrounded by dancers in shiny red costumes Robbie Williams welcomed fans and footballers alike.
Robbie Williams is a 44-year old an award-winning British pop icon.
Tasked with entertaining the planet on Thursday afternoon is a certain Robert Peter Williams who will perform two songs with Russian opera singer Aida Garifullina.
It was hard to miss - Williams did it right into the camera that was in front of him while singing his hit "Rock DJ".
"I am not saying Robbie Williams at the World Cup is the worst thing I have ever seen but it is definitely up there", one viewer wrote.
He didn't manage to steer clear of controversy entirely, however, after raising his middle finger to the cameras as he left the pitch.
It didn't get much better for the Crown Prince as Russian Federation romped home to a 5-0 win, which raised hopes the low-ranked hosts might progress into the tournament's later stages.