Jenson Button and Lewis Hamilton should be prepared to struggle during the 2011 F1 season, according to commercial rights holder Bernie Ecclestone.
The British pair have endured a difficult lead up to the new season after McLaren struggled with both pace and reliability with the MP4-26 during testing in Spain.
As a result of the poor testing performance, team boss Martin Whitmarsh has revealed that the car will undergo 'dramatic changes' ahead of the first race of the year in Australia this weekend but Ecclestone warned that both Button and Hamilton can expect to struggle if the changes don't have the desired effect.
"Lewis and Jenson are going to have a bit of a struggle this year I think, but having said that, Ferrari's Fernando Alonso and any of the other top guys will have a problem,” he told BBC Sport
. "It won't be easy, I don't think anyone is going to walk away with it. A lot of these things depend on the car.
"I have no doubt in my mind that both Jenson and Lewis will perform very, very well, if the car is capable of doing that. As drivers they are both capable of winning the championship and they have done in the past."
Ecclestone added that, based on pre-season testing, his money would be going on one of three drivers to secure the championship crown.
"Looking at it now you would have to say one of the Red Bull guys will be champion or Alonso but as I said, it won't be easy," he said. "You've got three guys there who could maybe do it. You never know about our English drivers but there's a big question mark over them."