Sebastian Vettel set the pace for Ferrari in a wet final Chinese Grand Prix practice session that was marked by limited running on Saturday.
The German quadruple world champion lapped the rain-drenched 5.4-kilometre Shanghai circuit in one minute 57.351 seconds on his only flying lap of the hour-long session.
Finn Valtteri Bottas, the first to go out onto the track after 15 minutes, was second for Williams 0.710 seconds adrift, while Force India's Sergio Perez went third 1.338 seconds off Vettel's benchmark.
Only 14 of the 22 cars risked setting a time with a flying lap in the treacherous conditions, choosing instead to save their sets of wet-weather tyres for a possible damp track during qualifying later on Saturday (0700 GMT).
The Mercedes pair of reigning champion Lewis Hamilton and championship leader Nico Rosberg limited their running to just installation laps.
McLaren duo Jenson Button and Fernando Alonso and Red Bull's Daniel Ricciardo and Daniil Kvyat also failed to set a time.
Rosberg, who leads the championship standings by 17 points after winning the opening two races of the season, heads into the weekend gunning for his sixth straight victory having closed out last year with a run of three consecutive wins.
Hamilton, who with four wins has won more races than anyone in China, is aiming to make it three consecutive victories in Shanghai.
But the Briton's challenge this weekend has been blunted by a five-place grid penalty for a gearbox change.
The highest he can start Sunday's race is sixth, leaving Rosberg the responsibility to score Mercedes' ninth straight pole position later on Saturday.