Shanghai (AFP) - Lewis Hamilton set the pace for Mercedes in free practice on Friday at the Chinese Grand Prix but fierce rivals Ferrari were just a whisker behind as the teams headed for another clash in this weekend's race.
The British reigning world champion topped the time sheet with a best lap of one minute and 33.482 seconds in Shanghai, just .007 seconds ahead of Ferrari's Kimi Raikkonen in windy, moist conditions.
Hamilton's teammate Valtteri Bottas was third, followed by season points leader Sebastian Vettel of Ferrari.
The annual battle between the sport's two giants has taken on an unexpected complexion, with Mercedes anxious for a win in Shanghai on Sunday after Vettel stunned the champions with wins in both Australia and Bahrain.
A mere 0.108 seconds separated the top four in Friday's practice.
Hamilton said it was "good to see all the times so close."
"But it means that we really need to bring our A game. We need everyone in the team to be on it throughout the weekend because it's a joint effort."
Added Bottas: "It's looking extremely close again with them (Ferrari) so I think tomorrow is going to be a close qualifying and for sure Sunday as well."
Both Vettel and Hamilton are chasing a fifth world title this year.
Mercedes are hopeful they can get things back on track on a Shanghai circuit where Hamilton is tough to beat.
The Englishman is easily the most successful driver in the 14-year history of the Chinese race with five wins, and he buoyed Mercedes hopes of a fightback by leading the pack in both of Friday's sessions.
Max Verstappen of Red Bull had to settle for fifth-fastest in practice, followed by Nico Hulkenberg driving for Renault.
Kevin Magnusson was seventh for Haas, ahead of Renault's Carlos Sainz and Verstappen's teammate Daniel Ricciardo.
Ricciardo said: "Overall, we aren't looking too bad and I hope we can be in the fight with Ferrari and Mercedes."
Two-time former world champion Fernando Alonso of McLaren rounded out the top 10.
Vettel raced to victory in Australia to open the Formula One season, following up with a tense triumph over Mercedes last weekend in Bahrain.
Ferrari have capitalised on a range of problems afflicting the champions, from software bugs to communication problems and grid penalties, but team principal Toto Wolff has vowed Mercedes will bring their "A game" in Shanghai.