Williams says Stroll hurt by power deficit in Brazil

Stroll's struggles at Interlagos, where he came home a frustrated last as teammate Felipe Massa shone to finish best-of-the-rest behind the big three teams, raised a few eyebrows and drew fresh criticism from Jacques Villeneuve.

But Williams technical chief Paddy Lowe insists that Stroll had little chance of doing much better because he had a power deficit as the result of having to go back to his third engine after a problem in final practice.

"The story of Lance this weekend is not great and not of his own making," explained Lowe.

"He had a gearbox failure in P3, which was due to a corruption of some of the electronic calibration. During that process, at high speed, it selected some low gears and revved the engine to over 18,000rpm – so the engine was finished.

"That was engine number four [the latest specification], so we put in engine number three and that is probably the one he will use for the rest of the year.

"Unfortunately engine number three is down on performance for a number of reasons compared to engine number four.

"It means that Lance was on the back foot with not a great qualifying position but also down on performance."

The biggest issue with using engine number three was that there was no longer any scope for Stroll to use magic modes to help in overtaking

"After stalling at the start, which was unfortunate, the biggest blow for Lance was getting stuck behind [Romain] Grosjean for far too long, which eroded his buffer and advantage to [Pierre] Gasly.

"And without the mode in the engine that he is missing – as in effect we have consumed a lot of the quotas in that engine because it was not supposed to be used again – it made overtaking very difficult.

"He then flat spotted a tyre in a desperate attempt to get past Grosjean, and that really then further ruined his race. It is one of the weekends which I am sure Lance will want to forget. But it was not kicked off by anything of his own doing."

Lowe said Williams did weigh up fitting a brand new fifth engine for Stroll on race morning, but decided that the extra cost of doing so was not worth the benefit it would bring.

Massa perfect

Although Stroll's result was disappointing, Lowe had nothing but praise for the way in which Massa finished seventh, having overtaken and then held off Fernando Alonso.

"Perfect," said Lowe. "We all remember Felipe's first retirement here last year which was very dramatic and you couldn't have scripted a better farewell, but this was actually far better because it was on the basis of a terrific drive.

"Best of the rest. And under extreme pressure, I think he probably didn't have the quicker car overall but he managed to claim that position by really fantastic skill and experience, especially by managing the life of the tyres he had."