A pair of Mark Webber's F1 rivals have expressed surprise with the Australian's 2011 season.
Although the 34-year-old seemed closer at Valencia recently, he has generally struggled to keep up with his Red Bull teammate Sebastian Vettel, who is utterly dominating the championship so far.
"Of course Sebastian is doing a very good job but I am a bit surprised with how difficult it seems to be for Mark," German Heidfeld, who drives for Renault, told the Herald Sun.
"Last year, even though Sebastian won the championship, Mark was able to be very strong in parts of the season. It seems to be a bit more difficult for him this season," he added.
And McLaren's Jenson Button told the Observer that Webber's form this year has surprised him as well.
"I think Seb's a great driver. He has proved that this season. But I am surprised he is that much quicker than Mark, so there is obviously something that is not working for Mark," said the Briton.
"He hasn't really been on the same pace as Sebastian this year, which surprises me as he is quick. He says he has got problems with the tyres, he is not getting to grips with them."
I am a bit surprised with how difficult it seems to be for Mark
Button admitted it will be "bloody hard" for anyone to challenge Vettel for the championship, while Webber and Ferrari's Fernando Alonso believe Red Bull could actually drive further away this weekend and beyond.
It is hoped the RB7 will be slowed at Silverstone by the blown exhaust clampdown, but Webber told the Daily Mail: "I'll be very surprised if the new rule changes the pecking order. My gut feeling is that they might even help us a bit."
And Alonso is quoted by Bild-Zeitung: "With the circuit characteristics of the coming races, Red Bull should definitely be better than the competition."
On his title hopes, he told formulasantander.com: "Being on average one second behind Red Bull all the time makes it impossible to come back."