McLaren fear over Lewis car

Lewis Hamilton may yet be robbed of a maiden Formula One world title by a mechanical failure.

With only the Brazil Grand Prix to come on Sunday week, Martin Whitmarsh, McLaren's chief executive, today admitted: "Our engines have generally been very reliable but you always worry because one slip and you can let a championship disappear."

Hamilton's team-mate, Heikki Kovalainen, suffered a blown engine in Japan two races ago and he was forced to retire from last weekend's Chinese Grand Prix with a hydraulic problem.

Adding to McLaren's concern is the F1 rule that engines must last for two races. Hamilton had a new engine in China, where he won in commanding fashion, and now he must use that same engine at Interlagos knowing it has already been subject to stress and strain.

By contrast, title rival Felipe Massa will have a fresh engine in his Ferrari and that could make him slightly more competitive.

Whitmarsh said: "It is very easy not to finish a Grand Prix. Things can go wrong. In terms of reliability issues there is, clearly, pressure."