Mercedes could be "the big surprise" of the 2011 season, according to Andy Soucek.
Speaking to Marca in Spain, the former F2 champion and 2010 Virgin tester was asked to give his verdict about the looming world championship.
"I see it between the two Red Bulls and Alonso, but watch out for Mercedes, who seem likely to be the big surprise," he said.
The Brackley based team apparently made a huge leap forwards with the W02's upgrade package at the final Barcelona test, with Michael Schumacher clocking the fastest time of the week.
"I am confident that we can compete for podium finishes, and I am hopeful we can fight for victories at some of the races," said Schumacher on Wednesday.