McLaren team principal Martin Whitmarsh’s misunderstanding of Formula One rules may have ultimately cost Lewis Hamilton a chance of winning the Spanish Grand Prix on Sunday.

Whitmarsh told Hamilton to stop on the Catalunya Circuit track after winning pole position in Saturday’s qualifying, fearing his driver could not provide a complete fuel sample.

Hamilton’s move was in breach of F1 rules as drivers must have enough fuel left to get back to the garages and provide a sample, and the 2008 F1 champion was subsequently excluded from qualifying, left to start from last place in the 24-car field.

“It’s difficult to measure fuel on board so you never know if it’s right or wrong. I took the call, (but) we must make sure that we’re right,” Whitmarsh said. “Whatever the outcome I was going to be embarrassed.”

Hamilton used a two-stop strategy, while leading teams employed three, to work his way through the field and finish eighth behind winner Pastor Maldonado of Williams. The Venezuelan driver, who was half a second off Hamilton’s pace on Saturday, won from the pole position assumed by Hamilton’s relegation.

“At the time … I was wrong, I didn’t anticipate as a consequence of that we would be starting from back of the grid,” Whitmarsh said. “In hindsight, I should have called it a different way and we should have just come in. Frankly, I didn’t expect the penalty we did see.”

Hamilton’s superb race left him third in the overall points standings, just eight points behind leaders Sebastian Vettel of Red Bull and Fernando Alonso of Ferrari.