Vote of confidence for Coulthard

But he again backed the Scot as speculation continued that his drive is under threat.

'I don't think the team could ask for a better performance [from David],' he said.

'There is no such thing as perfection. He is a little frustrated after Imola which was a race he should have won - and he knows that - but at the same time, how can we fault his performance in France and several other times this year? It was a great drive.'

Coulthard's car has broken down four times in seven races - most recently while he was leading the French Grand Prix two weeks ago.

'I don't believe in luck. We try and achieve equality of equipment for our drivers and there is no reason we can see in the analysis of the faults as to why they should appear on David's car [only].

'We are very thorough. 70 per cent of the failures are first-time failures. It was an electronic power box at the French Grand Prix and it is the first time we have had a problem of that type.

'We are becoming overly sensitive to the fact that he seems to be having the problems but we cannot try and harder than we are. It is as frustrating for us as it is for David. It doesn't look good for us either.'