By Alan Baldwin LONDON (Reuters) -Frenchman Laurent Mekies got down to work as Red Bull team principal on Thursday, a day after replacing Christian Horner, and recognised big challenges ahead for the once-dominant former champions.

Red Bull’s Formula 1 team is changing team directors for the first time since it was founded 20 years ago, after Christian Horner's sacking sent shockwaves through the sport on Wednesday.

Job number one is to keep hold of Max Verstappen.