Rosberg, Massa set the pace in China

Nico Rosberg led team-mate Lewis Hamilton in a Mercedes one-two in opening Chinese Grand Prix practice, as the squad returned to the scene of its first modern-era Formula 1 victory one year ago.

Warring Red Bull duo Mark Webber and Sebastian Vettel were next up, but a second off the Mercedes' pace.

Mercedes took charge on the last lighter-fuel runs going into the final half-hour of the session.

Rosberg initially put in a 1m37.872s to knock Felipe Massa's Ferrari off the top spot.

This mark was then pipped by Webber, who went 0.2s faster just a minute later.

But Rosberg had more speed to come. Despite signs of tyre graining and being eight laps into a stint, he unleashed a 1m36.904s, backed off for a lap, then delivered the best lap of the morning with a 1m36.717s.

Mercedes then appeared to have superior pace on the race stint simulations in the final half-hour, although fuel load variations inevitably skew this picture.

Hamilton was ultimately 0.454s down on his team-mate, but 0.487s clear of Webber. Three tenths of a second split the two Red Bulls in third and fourth.

In the second practice, it was Felipe Massa who put Ferrari on top as Rosberg had to settle for fourth this time, while Kimi Raikkonen and Fernando Alonso took second and third places.

Initially Rosberg and Mercedes resumed their commanding morning form by setting the initial pace, while team-mate Lewis Hamilton was next up.

The soft tyre runs started early, with Mark Webber switching from the medium rubber just 20 minutes in.

He used his new Pirellis to outpace Rosberg by 0.6s and claim first place, although the German soon retaliated with his own soft-tyre dash and got back in front.

But the second half of the afternoon was all about Ferrari and Massa.

A 1m35.340s from Massa on the soft tyres put him in front, and that was where he stayed.

More impressively, he maintained his speed better than most on his subsequent long run with medium tyres, on a day when radio complaints about graining were perhaps even more prevalent than usual.

Rosberg was eventually pushed down to fourth place as Raikkonen emerged as Massa's closest rival, getting within 0.152s.

Fernando Alonso increased Ferrari's satisfaction with third place, albeit 0.4s off his team-mate.

Rosberg and Webber completed the top five, while Jenson Button showed encouraging form for McLaren again in sixth, ahead of Hamilton.

2013 Chinese GP Free Practice 1 classification

Pos  Driver               Team/Car              Time       Gap       Laps
 1.  Nico Rosberg         Mercedes              1m36.717s            21
 2.  Lewis Hamilton       Mercedes              1m37.171s  + 0.454s  20
 3.  Mark Webber          Red Bull-Renault      1m37.658s  + 0.941s  21
 4.  Sebastian Vettel     Red Bull-Renault      1m37.942s  + 1.225s  20
 5.  Fernando Alonso      Ferrari               1m37.965s  + 1.248s  17
 6.  Jenson Button        McLaren-Mercedes      1m38.069s  + 1.352s  24
 7.  Felipe Massa         Ferrari               1m38.095s  + 1.378s  14
 8.  Adrian Sutil         Force India-Mercedes  1m38.125s  + 1.408s  21
 9.  Romain Grosjean      Lotus-Renault         1m38.398s  + 1.681s  17
10.  Paul di Resta        Force India-Mercedes  1m38.561s  + 1.844s  15
11.  Kimi Raikkonen       Lotus-Renault         1m38.790s  + 2.073s  16
12.  Jean-Eric Vergne     Toro Rosso-Ferrari    1m39.057s  + 2.340s  19
13.  Pastor Maldonado     Williams-Renault      1m39.158s  + 2.441s  22
14.  Nico Hulkenberg      Sauber-Ferrari        1m39.180s  + 2.463s  21
15.  Daniel Ricciardo     Toro Rosso-Ferrari    1m39.336s  + 2.619s  19
16.  Sergio Perez         McLaren-Mercedes      1m39.360s  + 2.643s  20
17.  Valtteri Bottas      Williams-Renault      1m39.392s  + 2.675s  20
18.  Esteban Gutierrez    Sauber-Ferrari        1m40.032s  + 3.315s  22
19.  Jules Bianchi        Marussia-Cosworth     1m41.966s  + 5.249s  16
20.  Max Chilton          Marussia-Cosworth     1m42.056s  + 5.339s  18
21.  Giedo van der Garde  Caterham-Renault      1m42.083s  + 5.366s  21
22.  Ma Qing Hua          Caterham-Renault      1m43.545s  + 6.828s  20
2013 Chinese GP Free Practice 2 classification

Pos Driver                Team                  Time      Gap        Laps
 1. Felipe Massa          Ferrari               1m35.340s             32
 2. Kimi Raikkonen        Lotus-Renault         1m35.492s  + 0.152s   32
 3. Fernando Alonso       Ferrari               1m35.755s  + 0.415s   30
 4. Nico Rosberg          Mercedes              1m35.819s  + 0.479s   35
 5. Mark Webber           Red Bull-Renault      1m36.092s  + 0.752s   31
 6. Jenson Button         McLaren-Mercedes      1m36.432s  + 1.092s   29
 7. Lewis Hamilton        Mercedes              1m36.496s  + 1.156s   39
 8. Adrian Sutil          Force India-Mercedes  1m36.514s  + 1.174s   32
 9. Paul di Resta         Force India-Mercedes  1m36.595s  + 1.255s   33
10. Sebastian Vettel      Red Bull-Renault      1m36.791s  + 1.451s   27
11. Sergio Perez          McLaren-Mercedes      1m36.940s  + 1.600s   16
12. Romain Grosjean       Lotus-Renault         1m36.963s  + 1.623s   31
13. Esteban Gutierrez     Sauber-Ferrari        1m37.103s  + 1.763s   22
14. Daniel Ricciardo      Toro Rosso-Ferrari    1m37.206s  + 1.866s   39
15. Jean-Eric Vergne      Toro Rosso-Ferrari    1m38.127s  + 2.787s   34
16. Valtteri Bottas       Williams-Renault      1m38.185s  + 2.845s   18
17. Nico Hulkenberg       Sauber-Ferrari        1m38.211s  + 2.871s   32
18. Pastor Maldonado      Williams-Renault      1m38.276s  + 2.936s   34
19. Jules Bianchi         Marussia-Cosworth     1m38.725s  + 3.385s   29
20. Giedo van der Garde   Caterham-Renault      1m39.271s  + 3.931s   21
21. Charles Pic           Caterham-Renault      1m39.814s  + 4.474s   27
22. Max Chilton           Marussia-Cosworth     1m43.227s  + 7.887s    5