Mercedes hit back at Ferrari in the first practice session of the Chinese Grand Prix with Lewis Hamilton and Nico Rosberg the only drivers to break the one minute, 40 second-barrier.
After Ferrari's Sebastian Vettel won the Malaysia Grand Prix from Hamilton and Rosberg at the end of last month, Mercedes seemed keen to make a statement at the Shanghai International Circuit on Friday.
Hamilton (1:39.033) and Rosberg (1:39.574) were the only drivers to break into the 1:30s in the opening practice session - with the reigning drivers' championship-winner claiming a gap over Vettel of 1.1secs, with Ferrari's German finishing third.
Vettel's team-mate Kimi Raikkonen (1:40.661) claimed fourth.
The majority of drivers had minor trips off the track in China, including Hamilton and Rosberg, while both Mercedes cars sent sparks flying on separate occasions due to some bumpy tarmac.
After failing to finish the opening two Grands Prix of the season, Lotus' Pastor Maldonado spent a large chunk of the session in second position but eventually had to settle for 11th with 1:41.335.
Lotus gave GP2 champion Jolyon Palmer - son of former F1 driver Jonathan Palmer - a run in the big boys' car in Shanghai and apart from a spin and overshooting a corner, did well to set the 15th-fastest lap of 1:41.967.
FP1 classification:
1. Lewis Hamilton (Mercedes) 1:39.033
2. Nico Rosberg (Mercedes) 1:39.574
3. Sebastian Vettel (Ferrari) 1:40.157
4. Kimi Raikkonen (Ferrari) 1:40.661
5. Felipe Nasr (Sauber) 1:41.012
6. Daniel Ricciardo (Red Bull) 1:41.029
7. Daniil Kyvat (Red Bull) 1:41.097
8. Carlos Sainz Jr (Toro Rosso) 1:41.112
9. Valtteri Bottas (Williams) 1:41.303
10. Felipe Massa (Williams) 1:41.304