Lewis Hamilton again proved a class above the rest and is on course to win his first Spanish Grand Prix after dominating practice.
Hamilton finished the day at Barcelona's Circuit de Catalunya almost half a second quicker than Mercedes team-mate Nico Rosberg, with the rest trailing well behind.
The 29-year-old, on a run of three straight victories for the first time in his Formula One career, was fastest by almost a second from McLaren's Jenson Button in the opening 90-minute run.
On that occasion only the hard compound Pirelli tyres were used, with Rosberg forced to sit out most of the session due to a cooling issue with his ERS (energy recovery system).
Rosberg halved the gap to Hamilton on the second outing when the switch to the faster medium rubber was made, but the gap was still significant.
Spanish Grand Prix - In pictures
Spanish Grand Prix - In pictures
1/10 Sunday race
Lewis Hamilton celebrates with his trophy after winning the Spanish Grand Prix
Nico Rosberg attempts to hunt down his Mercedes team-mate in the battle for Spanish Grand Prix glory
3/10 Saturday final practice
Spanish hero Fernando Alonso prepares to head out where he will receive the usual ferocious support he has grown used to in Barcelona
4/10 Saturday final practice
Nico Rosberg finished fastest in final practice for the Spanish Grand Prix ahead of Lewis Hamilton
5/10 Saturday final practice
Williams' Felipe Massa walks through the pit-lane ahead of qualifying
6/10 Friday second practice
Esteban Gutierrez negotiates the sweeping turns 1 and 2 in his Sauber
7/10 Friday second practice
Daniel Ricciardo enjoyed a far more successful practice session as he ran behind the Mercedes pair in third position
8/10 Friday first practice
A concerned Sebastian Vettel keeps guard over his broken down Red Bull as he looks on with a fire extinguisher at the ready
9/10 Friday first practice
Sebastian Vettel pushes his Red Bull after it grinds to a halt on the Catalunya track
10/10 Friday first practice
Lewis Hamilton leads the first practice at the Spanish Grand Prix
Hamilton finished with a time of one minute 25.524 seconds, 0.449secs clear of Rosberg, with Red Bull's Daniel Ricciardo the only other driver to be within a second of the Briton.
As for team-mate Sebastian Vettel, the reigning four-times champion had the afternoon off as his car incurred a wiring loom fault after four laps of the first session which sidelined him for all of the second.
Behind Ricciardo, Ferrari's Fernando Alonso was again fourth fastest, as was the case in the morning when president Luca Di Montezemolo arrived to cast an eye over proceedings.
It is a year since Ferrari last won a race, with Alonso taking the chequered flag at this track last May, but there is unlikely to be any repeat as the Spaniard finished 1.5secs down on Hamilton.
Alonso had team-mate Kimi Raikkonen in close attendance, followed by McLaren duo Kevin Magnussen and Button.
In the second session Button finished almost 2.3secs down, a huge gap even though the McLaren carries the same Mercedes power unit that is allowing the works team to take control.
The top 10 was completed by Williams' Felipe Massa, the Lotus of Pastor Maldonado and Russian rookie Daniil Kvyat in his Toro Rosso, the latter almost 2.5secs back.
Marussia's Max Chilton, on a run of 23 consecutive finishes, endured a troubled session in which he was plagued by engine trouble before beaching his car in the gravel late on.
Chilton finished 19th on the timesheet, 5.6secs behind Hamilton, but at least ahead of Caterham duo Kamui Kobayashi and Marcus Ericsson.
Positions after second practice:
1 Lewis Hamilton (Gbr) Mercedes 1min 25.524secs
2 Nico Rosberg (Ger) Mercedes 1:25.973
3 Daniel Ricciardo (Aus) Red Bull 1:26.509
4 Fernando Alonso (Spa) Ferrari 1:27.121
5 Kimi Raikkonen (Fin) Ferrari 1:27.296
6 Kevin Magnussen (Den) McLaren 1:27.788
7 Jenson Button (Gbr) McLaren 1:27.811
8 Felipe Massa (Bra) Williams 1:27.824
9 Pastor Maldonado (Ven) Lotus 1:27.866
10 Daniil Kvyat (Rus) Toro Rosso 1:28.049
11 Nico Hulkenberg (Ger) Force India 1:28.074
12 Jean-Eric Vergne (Fra) Toro Rosso 1:28.246
13 Adrian Sutil (Ger) Sauber 1:28.284
14 Valtteri Bottas (Fin) Williams 1:28.698
15 Esteban Gutierrez (Mex) Sauber 1:29.105
16 Sergio Perez (Mex) Force India 1:29.129
17 Romain Grosjean (Fra) Lotus 1:29.493
18 Jules Bianchi (Fra) Marussia 1:29.991
19 Max Chilton (Gbr)Marussia 1:31.148
20 Kamui Kobayashi (Jap) Caterham 1:31.338
21 Marcus Ericsson (Swe) Caterham 1:31.586
22 Sebastian Vettel (Ger) Red Bull No time