Red Bull team principal Christian Horner has declared Mercedes to be the pre-season favourites to win the Formula 1 constructors' title in 2014.
Red Bull have won the teams' and drivers' titles for the last four years, but have struggled with reliability problems in the pre-season testing.
Horner told Sky Sports News: "You'd have to say that Mercedes are the favourites, or that Mercedes-powered teams are absolutely the favourites.
"We are on the back foot, but it's a long year, a tough championship and it's not all won in winter testing.
"It's obviously not where we wanted to be, but it's where we are and it's a question of just getting on with it."
Mercedes have completed more laps in the first two pre-season tests than any other team.
