McLaren's Lewis Hamilton set down a marker for the weekend with the quickest time of the first two practice sessions for the Chinese Grand Prix yesterday.

The former world champion, who finished sixth in the last two races, swept around the 5.451 kilometre circuit in one minute 35.217 seconds on a cool but sunny day in Shanghai.

German Nico Rosberg was second fastest for Mercedes, 0.248 seconds behind Hamilton but ahead of team-mate and reigning world champion Jenson Button.

"I come out with a positive feeling but you never know what's going to happen tomorrow," said Hamilton, who started 20th in Malaysia after his team misread the weather in qualifying.

"We've just got to get our heads down and get the best possible qualifying position."

Michael Schumacher completed the dominance of the Mercedes-powered cars with the fourth fastest lap ahead of the Red Bull duo of Sebastian Vettel and Mark Webber.

Button said he still feared the pace of the Red Bulls, who finished one-two in the last race in Malaysia and at Shanghai last year.

"I don't think the Red Bulls have shown their hands yet, but they will be quick, they are still the ones to beat," he said.

The largely uneventful second session followed a dramatic morning when Fernando Alonso's Ferrari came to a halt in flames and Toro Rosso's Sebastien Buemi survived a spectacular crash.

Twice world champion Alonso, who failed to finish the last race in Malaysia because of an engine failure, said the blow up had been expected.

"The engine I had this morning was the one we had changed after qualifying in Bahrain and we knew sooner or later it could break," said the Spaniard, whose championship leading team-mate Felipe Massa had the 11th fastest time.

Buemi's front wheels exploded off his Toro Rosso at the end of the main straight late in the first session, both tyres clearing the safety fence as the Swiss came to a halt in the gravel.

The session was red flagged and there was a 10-minute break.

Despite finishing second fastest in both sessions, Rosberg said Mercedes still trailed Red Bull and he was not confident of another podium to match his third place in Malaysia.

"Not if everything goes normally, but with a bit of luck, of course, yes," he said.