Red Bull motorsports advisor Helmut Marko has outlined Mercedes and "special" Lewis Hamilton as the biggest threat to the team ahead of the 2023 season.
The Austrian underlined Lewis Hamilton's effect on the Silver Arrows despite the Briton experiencing the first winless year of his F1 career this year.
In contrast, Red Bull waltzed to a first title double since 2013, with Max Verstappen beating Ferrari's Charles Leclerc by 146 points in the drivers' standings, whilst the Scuderia finished a staggering 205 adrift in the constructors'.
This was despite the Italian marque being labelled as favourites after the stunning start to the season for the F1-75 that looked head and shoulders above the field.
Mercedes, meanwhile, endured a difficult year but raised optimism with a strong end to the campaign, including a maiden victory for George Russell in the penultimate round in Brazil.
Whilst Red Bull and Mercedes head into the new season with solid platforms and plans, Ferrari is in a transitionary period, with Fred Vasseur replacing Mattia Binotto as team principal.
Asked who he felt would be the main challenger to Red Bull next year, Marko told AMuS: "Definitely Mercedes.
"They are the more stable team and they have Hamilton.
"Even though it [results] might have gone down this year, he is a very special driver. In between, he has shown time and again with his lap times that he is a top man.
"That [Mercedes] is simply a much stronger package than Ferrari."