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 sacked Christian Horner, Formula One's longest-serving active team principal and one of the most successful of all time, and replaced him on Wednesday with Racing Bulls' Laurent Mekies.

Horner is the latest in a series of high-profile executives to leave the team over the last year and a half.