Mercedes drivers Nico Rosberg and Lewis Hamilton secured a one-two in the first practice session in Shanghai on Friday ahead of the Chinese Grand Prix, but Ferrari fought back in the second as Kimi Raikkonen and Sebastian Vettel topped the timesheets.
It was a disrupted first practice as tyre failures for Williams's Felipe Massa and Renault's Kevin Magnussen resulted in the session stopping for 30 minutes.
Massa suffered two left-rear wheel failures, while Magnussen had a suspected broken left rear suspension, but the teams could not immediately confirm the problems.
On the track, Rosberg, who is the championship leader following wins in Australia and Bahrain, clocked the fastest time of 1:38.037, while his rival and teammate Hamilton was second fastest on 1:38.183.
In the second session, Esteban Gutierrez had trouble with his Haas as his rear brakes caught on fire, but the driver managed to safely return to the pits.
Rosberg clocked the quickest time on his first run-out, but it was Ferrari duo Raikkonen and Vettel who gave Mercedes something to think about as they topped the standings.
Raikkonen recorded a time of 1:36.896, while Vettel's fastest time was 1:37.005
First practice standings
1. Nico Rosberg (Mercedes)
2. Lewis Hamilton (Mercedes)
3. Sebastian Vettel (Ferrari)
4. Daniel Ricciardo (Red Bull)
5. Kimi Raikkonen (Ferrari)
6. Daniil Kvyat (Red Bull)
7. Carlos Sainz Jr (Toro Rosso)
8. Jenson Button (McLaren)
9. Nico Hulkenberg (Force India)
10. Max Verstappen (Toro Rosso)
11. Sergio Perez (Force India)
12. Fernando Alonso (McLaren)
13. Valtteri Bottas (Williams)
14. Romain Grosjean (Haas)
15. Marcus Ericsson (Sauber)
16. Rio Haryanto (Manor)
17. Jolyon Palmer (Renault)
18. Pascal Wehrlein (Manor)
19. Felipe Nasr (Sauber)
Second practice standings
1. Kimi Raikkonen (Ferrari)
2. Sebastian Vettel (Ferrari)
3. Nico Rosberg (Mercedes)
4. Lewis Hamilton (Mercedes)
5. Daniel Ricciardo (Red Bull)
6. Max Verstappen (Toro Rosso)
7. Nico Hulkenberg (Force India)
8. Carlos Sainz Jr (Toro Rosso)
9. Sergio Perez (Force India)
10. Valtteri Bottas (Williams)
11. Fernando Alonso (McLaren)
12. Jenson Button (McLaren)
13. Daniil Kvyat (Red Bull)
14. Felipe Massa (Williams)
15. Jolyon Palmer (Renault)
16. Romain Grosjean (Haas)
17. Pascal Wehrlein (Manor)
18. Marcus Ericsson (Sauber)
19. Rio Haryanto (Manor)
20. Felipe Nasri (Sauber)
21. Esteban Gutierrez (Haas)