Jenson Button has tipped his former team to be an outside chance for ultimate glory in 2012.
Just before the Brackley based team became Mercedes for the start of 2010, Button won the world championship at the wheel of his 'Brawn GP' car.
That team is still fronted by Ross Brawn, with Michael Schumacher and Nico Rosberg now in the drivers' seats for a third consecutive season next year.
"Usually it's the three very strong teams at the front, which is Red Bull, Ferrari and us," said Button, who in his McLaren finished the 2011 season as runner-up to Red Bull's Sebastian Vettel.
"But we have to watch out for Mercedes," he told the German news agency SID. "They have been preparing for 2012 for half of this season -- as they did before I became world champion."
Schumacher, however, is more cautious, despite admitting that members of the German team "all hope" Button is right.
"More likely is that we will improve in the coming year so that we can fight with our own power for the podium places," the seven time world champion, who turns 43 in January, is quoted by Sport Bild.
McLaren test driver Pedro de la Rosa agrees, although he hopes Ferrari, McLaren and Mercedes can all pose a challenge to Red Bull next year "for the sake of the championship".
"I take the more humble view by accepting that the exhaust blowing was just one example of the quality and the creativity of the Red Bull team," he is quoted by Marca sports newspaper.
"Without it in 2012, I have little doubt that Red Bull will surprise us again with something ingenious."