Red Bull is looking particularly strong and will be a "different animal" this season with Sergio Perez alongside Max Verstappen, seven times Formula One world champion Lewis Hamilton said on Sunday.
Experienced Mexican Perez, a winner in Bahrain last December, has joined Red Bull from the team that was Racing Point and is now Aston Martin as a replacement for Thai racer Alexander Albon.
Hamilton, whose Mercedes team started the last day of the three-day test in Bahrain with fewer laps completed than others after a gearbox problem on Friday, said he was excited at the prospect of a real battle.