Lewis Hamilton: Mercedes F1 clutch 'catching us out' in Canadian GP

Polesitter Lewis Hamilton was slow off the line, with team-mate Nico Rosberg only marginally better, allowing Ferrari's Vettel to take the lead into the first corner.

It was not the first incident this season of poor starts compromising Hamilton and Rosberg, with Mercedes conducting an investigation earlier in the year as well.

"The clutch was warm, had low torque, so I let the clutch out and it didn't deliver the torque," explained Hamilton.

"Compared to Nico, his torque was not as expected, but he still had better torque.

"So my clutch was just slipping. I did the procedure exactly as I was asked.

"They're going to investigate and try to understand why.

"They don't quite understand it, so we're going to work on it.

"Having seen [the data], I'm happy I didn't make any mistakes, but this clutch is definitely catching us out."

For this season the clutch start procedure has changed, with drivers now operating a single rather than a double clutch, and with no guidance from the pitwall.

Hamilton, though, is at a loss to understand why the Mercedes' starts have been so hit and miss.

"All weekend the starts have been fantastic, but the clutch is not the same all the time," he added.

"The formation start was fantastic. I let the clutch out and it was perfect - perfect torque, no wheelspin.

"I came round, I did exactly what they asked me to do, and then the damn thing just slipped.

"It's a priority for Nico as well, when we talk about priorities of things we can work on."