Mercedes, who unlike the Prancing Horse only used Pirelli’s medium compound rubber, were half a second back, with championship leader Nico Rosberg edging Lewis Hamilton in the fight for third.
Max Verstappen, making his debut for Red Bull, was a solid sixth behind new team mate Daniel Ricciardo, while Toro Rosso returnee Daniil Kvyat ended up in 12th, four spots and half a second down on the other STR11 of Carlos Sainz.
Esteban Ocon, participating in FP1 in place of Jolyon Palmer, had a disappointing session for Renault, completing just six untimed laps before being halted by a technical issue.
Sergio Perez also experienced mechanical woes, though Force India were able to repair his car and return the Mexican to the track before the end of the session.
While the top quartet were in a league of their own – and the Red Bulls completed a mini-group with Williams’ Valtteri Bottas – it was very close behind, with less than one second covering Sainz in eighth down to Perez in 14th.
That grouping included the second Williams of Felipe Massa, McLaren’s Fernando Alonso, Renault’s Kevin Magnussen, Kvyat and Perez’s team mate Nico Hulkenberg.
While Alonso therefore earned McLaren’s heavily-revised MP4-31 a place in the top 10, team mate Jenson Button was far less happy. He finished 19th – 1.4s down on Alonso – and complained of handling issues during the 90-minute session.
Haas’s Romain Grosjean was also unhappy, labelling his car a ‘disaster’ in low-speed corners. The Frenchman – who along with team mate Esteban Gutierrez did not set a time in the opening half of the session – wound up 16th, with Gutierrez one spot further back.
The session was also notable for a couple of off-track moments in Turn 1 for Hamilton, whose Mercedes is using a new MGU-H after his recent problems, one for Raikkonen, and a spin by Massa in Turn 5.
|Spanish Grand Prix First Practice Results|
|Pos.||Car #||Driver||Best Time||Behind||Gap||Laps|
|8||55||Carlos Sainz Jr||1:26.078||-2.127||-0.406||19|