Sebastian Vettel kept Ferrari on top of the Chinese GP timesheet as heavy rain arrived to saturate the Shanghai circuit for final practice on Saturday morning.
However, despite the likelihood of the later qualifying hour also being disrupted by wet weather, Mercedes chose not to set any timed laps with Lewis Hamilton and Nico Rosberg.
Rain was heavily falling at the start of final practice and it was 15 minutes until cars were seen on track, with Williams the first team to dispatch theirs on the full wet tyre.
Conditions slowly improved to the point where intermediates could be used - before the rain stopped completely - and Vettel went quickest with a lap of 1:57.351, which was seven tenths quicker than second-fastest man Valtteri Bottas.
But in another potential reliability concern for Ferrari after issues in each of the first two races, Vettel reported a gearbox glitch during the course of his fastest lap. He made his way back to the pit lane and then sat out the remainder of the session.
The Mercedes pair were among eight drivers who did not set a lap time, with Hamilton and Rosberg only entering track for exploratory laps on the full wet rubber in the early stages.
With the timesheet largely irrelevant, Sergio Perez was third for Force India ahead of Toro Rosso's Carlos Sainz and the Haas of Esteban Gutierrez.
Britain's Jolyon Palmer was sixth for Renault, but suffered a right-rear puncture with bodywork rubbing against the tyre thought to have caused the problem. The Enstone team had suffered a left-rear puncture on Kevin Magnussen's car on Friday and made suspension changes as a result.
McLaren, eyeing a first Q3 appearance since their reunion with Honda this weekend, did not set any lap times themselves - with Red Bull employing the same tactic.
The Milton Keynes-based team usually run strongly in wet conditions and could spring a surprise if the rain returns for qualifying at 8am BST.
Practice Three timesheet
1. Sebastian Vettel, Ferrari, 1:57.351
2. Valtteri Bottas, Williams, 1:58.061
3. Sergio Perez, Force India, 1:58.689
4. Carlos Sainz, Toro Rosso, 1:58.800
5. Esteban Gutierrez, Haas, 1:59.526
6. Jolyon Palmer, Renault, 1:59.677
7. Kevin Magnussen, Renault, 1:59.761
8. Pascal Wehrlein, Manor, 1:59.694
9. Max Verstappen, Toro Rosso, 2:00.150
10. Nico Hulkenberg, Force India, 2:00.158
11. Felipe Nasr, Sauber, 2:00.197
12. Kimi Raikkonen, Ferrari, 2:00.812
13. Felipe Massa, Williams, 2:02.438
14. Rio Haryanto, Manor, 2:02.732
15. Jenson Button, McLaren, No time
16. Fernando Alonso, McLaren, No time
17. Romain Grosjean, Haas, No time
18. Daniil Kvyat, Red Bull, No time
19. Nico Rosberg, Mercedes, No time
20. Daniel Ricciardo, Red Bull, No time
21. Lewis Hamilton, Mercedes, No time
22. Marcus Ericsson, Sauber, No time
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