Hamilton fastest in Russia, Vettel stops

SOCHI, Russia: Formula One world champion Lewis Hamilton was top of the timesheets in Russian Grand Prix practice on Friday after Mercedes team mate Nico Rosberg set the early pace and Ferrari suffered reliability problems.

Rosberg, chasing his seventh win in a row and fourth of the season, was quickest in the morning around the Olympic Park used for the 2014 Winter Games in the Black Sea resort.

The championship leader dropped to third in the afternoon, however, with Hamilton setting a best time of one minute 37.583 seconds on supersoft tyres compared to Rosberg´s 1:38.450.Ferrari´s Sebastian Vettel stopped on track during the second session but was still second fastest.

"I think we´re looking strong here, but we need to keep working hard if we are to try and stay ahead of the Ferraris," said Hamilton. "They look like they might be another step closer this weekend."

Hamilton is the only driver to have won in Russia since the race´s debut in 2014 and he needs to complete the hat-trick on Sunday to eat into his team mate´s hefty 36 point lead after just three of the 21 races.

The Mercedes pair, who have won 35 of the last 41 races between them, were comfortably ahead of the rest in the morning but Vettel showed pace for Ferrari before he hit problems.

The four-times world champion, whose team have suffered power unit problems in two races this season, stopped with an hour to go.

Ferrari´s Kimi Raikkonen was fourth in both practices.