Mercedes driver Lewis Hamilton admits he doesn't know why he suffered another poor start in Sunday's Canadian Grand Prix, as he did "the normal procedure", but it "just didn't go anywhere".

Hamilton has struggled to get off the line a number of times this season, and while he did still come through to win in Montreal, cutting team-mate Nico Rosberg's lead in the Drivers' Championship back to 9 points, it is a concern for the Briton as he looks to try and secure his fourth world title.

"Yeah, the start was, I don't understand it," he replied, when asked what happened. "This time I really don't understand because practices have been good, the formation lap was amazing, dropped the clutch and the thing pulled away perfectly. Yeah, I stopped [before the start], did the normal procedure, let the clutch out and it just didn't go anywhere. I'm really lost as to know what [happened]...

"Obviously I had really good pace and that really got in the way. Had it been a longer straight, I would have been a sitting duck. I don't really know what to say about it."

Meanwhile, Hamilton added that into Turn 1 he struggled as he had understeer and cold front tyres and that was why there was contact with Rosberg.

"Into turn one, these tyres, these ultrasofts, he [Sebastian Vettel] was lightning on the first lap but me, I had no grip," Hamilton continued.

"I got to turn one and I had this understeer and I thought that it was going to continue for the rest of the lap. I think the guys behind me were also tiptoeing.

"Very close, obviously, between me and Nico [too] which wasn't intentional, but fortunately none of our cars were damaged."