Robin Thicke is filming a music video with Will Ferrell's 'Anchorman 2' character Ron Burgundy.

The 'Blurred Lines' singer and the legendary star have already recorded a cover of Christopher Cross' 1980 hit 'Ride Like The Wind' for the movie's soundtrack.

Now sources say they want to make a video to promote the song but are struggling to find the time.

An insider told the New York Post's Page Six: ''Everyone's on board for a proper music video, but Will's concerned about his schedule.''

The insider says he fears Ron Burgundy will be overexposed but would like Robin to join him on one of his upcoming TV appearances to promote the film.

It was hoped he would appear on late-night talk show 'Conan' last week but it would have cost up to $100,000 to get Robin out of previous engagements and to Los Angeles in time.

The next opportunity would be during Will's appearance on 'Jimmy Kimmel Live' on December 19 and negotiations are still ongoing with Robin's record label Interscope.

Will has already appeared as the 1970's San Diego anchorman in a blitz of promotional spots for the movie, including a spoof with Daft Punk for the European Music Awards in Amsterdam.

'Anchorman 2' hits cinemas on December 20.