F1 Canadian GP: Lewis Hamilton leads practice as Mercedes dominates

Mercedes duo Hamilton and Nico Rosberg dominated the opening period, finishing well ahead of the chasing pack.

Hamilton was 0.415 seconds faster than Rosberg, who was over a second ahead of the Lotus of Romain Grosjean in third.

Mercedes-powered cars dominated practice at Montreal's Circuit Gilles-Villeneuve, which is characterised by three long straights. Four of the top five fastest cars in the session were powered by the Mercedes powerplant.

Force India's Nico Hulkenberg was fourth fastest, followed by the Ferrari of Sebastian Vettel and the Williams of Felipe Massa.

Daniil Kvyat was next up in his Toro Rosso, finishing the session in seventh place ahead of the second Lotus of Pastor Maldonado and McLaren's Fernando Alonso.

Hamilton set the early pace on the soft tyre and remained at the top of the timing sheets for the next 90 minutes.

When pushing harder with half an hour to go he spun at the Turn 10 hairpin but was able to continue unharmed.

Shortly afterwards he mentioned on his team radio that he was losing time with his upshifts.

Carlos Sainz Jr had an eventful session. First he locked-up and spun his Toro Rosso into Turn 1 before continuing, but with 10 minutes to go he stopped at the bottom of the pitlane and was pushed back to his garage by his mechanics.

Half a dozen cars outbraked themselves into the final chicane and had to familiarise their way around a new bollard and lane to return to the track.

Jenson Button suffered problems early on when he radioed back to his garage unable to shift out of second gear.

After a slow installation lap he returned to his McLaren pit and he sat the first half of the session with a gearbox issue.

In the end he was able to complete 25 laps and set the 15th fastest time.

Practice started in overcast conditions, but quickly brightened up. During the session there was a bizarre sight as marshals were removing small metal staples from an area of pitlane where a carpet had been laid during a previous event at the venue.

The second 90-minute session commences at 2pm local time with some forecasts still predicting rain.

PRACTICE RESULTS: