Mercedes driver Lewis Hamilton recovered from an early suspension problem to set the fastest practice time at the Chinese Grand Prix, narrowly edging Fernando Alonso of Ferrari.
Hamilton only completed nine laps in the morning session due to problems with the car, but came back in the afternoon to set a best time of 1 minute, 38.315 seconds around the Shanghai International Circuit.
Alonso, who had the fastest time in the morning session, was 0.141 seconds behind Hamilton under the watch of new team principal, Marco Mattiacci, who arrived in Shanghai to take charge following Stefano Domenicali's abrupt departure this week.
Hamilton's teammate, Nico Rosberg, had the third-fastest practice time, with Red Bull drivers Daniel Ricciardo and Sebastian Vettel fourth and fifth, respectively.
Mercedes has been the team to beat so far this season, with Hamilton winning in Bahrain and Malaysia and Rosberg in Australia. Only an engine problem on Hamilton's car in the opening race in Melbourne has prevented three successive one-two finishes.
Ferrari has lagged behind Mercedes this season following the sport's switch to new V6 turbo hybrid engines and new fuel-saving regulations. The slow start prompted Ferrari to part ways with Domenicali after six years, replacing him with Mattiacci, formerly president of Ferrari North America.