Toto Wolff is warning that Mercedes may be overtaken in 2021.
His counterpart at Red Bull, however - Christian Horner - warns that the reigning champions remain the clear favourites to keep dominating this year.
"They had an incredible car last year and the main features of it will be at the start this year as well," he said.
Wolff, however, thinks the mandatory changes to floor designs for 2021 could actually shake up the pecking order.
"The change to the floor, from which a part has to be cut out basically, is decisive in a technical sense," the Mercedes team boss told Speed Week.
"It has forced a rethink of the entire concept. So we cannot rule out that Red Bull or Aston Martin will come up with a better solution."