Sir Jackie Stewart, Britain's three-time Formula One champion, wants to see Nico Rosberg beat Lewis Hamilton to next year's title.
Hamilton emulated Stewart by claiming his third championship at last month's United States Grand Prix.
Stewart, 76, was at the Austin race to congratulate Hamilton, who has dominated the sport this season, on his achievement.
But asked if he expects Hamilton to be crowned a four-time world champion next year, Stewart, speaking from the Abu Dhabi paddock, replied: "If Mercedes retain the leadership that you almost expect from Mercedes, I'm afraid you could be finding the same thing, but don't count out Rosberg.
"There is nothing to stop Rosberg winning. He is quick. We have seen him have so many pole positions and he is smoother (than Hamilton).
"I'd like to see him win the title. That would be very good."
Hamilton has held the upper hand over Rosberg for much of the season, and won the title in Austin after banging wheels with his team-mate at the opening corner.
A furious Rosberg subsequently accused the Briton of "extremely aggressive" driving and even threw a cap at his team-mate ahead of the podium celebrations.
Stewart added: "Lewis is quite aggressive so therefore he has won more races because of that aggression, but sometimes that can bite you also.
"Nico is good and there is no question about it. The trouble is you have to be very good and he has got to just step up that little bit extra."
Since Hamilton clinched his successive championship triumph, Rosberg has won the ensuing races in Mexico, Brazil and Abu Dhabi to complete a hat-trick of consecutive victories for the first time in his career.
Mercedes have been Formula One's class act for the past two years - winning 32 of the last 38 races - and with limited changes to the regulations over the winter it is expected that they will lead the way once more in 2016.
"Mercedes will eventually be beaten, but I'm not sure the rest of the teams are really good enough yet to be able to take them on," Stewart added. "More than a second a lap is too big a gap and that's not good racing.
"You never know, another year, you have an Adrian Newey suddenly coming up with something and the whole scene can change. So, you can't take anything for granted.
"But while Mercedes' money is there - both in engine and their chassis - it is going to be difficult for them to be beaten."
Christian Horner, the Red Bull team principal who oversaw four consecutive driver and team triumphs between 2010 and 2013, concurred with Stewart.
Horner, who last week called for a shake-up to the rules in a bid to make the sport more competitive, said: "I think the regulations are extremely stable for next year and obviously Mercedes will inevitably carry on the dominance, such is their margin.
"I think predictable and serial results and serial winning is difficult for any sport. We were accused of it, but we never enjoyed the continuation of success or longevity of success."
Source: PA-WIRE
