Max Verstappen has topped opening practice for the Spanish Grand Prix with Red Bull again looking the dominant force.

Sergio Perez was second best, almost 0.8s away from his team-mate at the end of the opening hour, with Esteban Ocon third for Alpine.

With seven of the 10 teams having updates this weekend, plus the addition of test tyres, it was a busy start to the session.

Most headed out on the test Pirelli rubber, though George Russell was one of the few to bolt on a set of mediums for his first run.

He sat fourth in the early moments, though times were rapidly changing as Fernando Alonso, Pierre Gasly, Perez, and Verstappen had spells at the top of the timesheets.

Red Bull had coated Perez’s rear wing with flo vis paint, the team having introduced a new diffuser this weekend.

There were changes too to the edge of the floor of the RB19 with the team keen to correlate the real-world impact with its findings in the wind tunnel and virtual world.

Ferrari had done the same on the back of Sainz’s car, along with the sidepod.

It was a key area of development for the Scuderia as it works to open the operating window and address the “peaking” handling referenced by Charles Leclerc in Monaco.

Verstappen complained of bouncing in his car, especially under braking into Turn 10, though the Dutchman sat atop the timesheet with a best of 1:15.945s.

That compared with a 1:19.828s set by Leclerc a year ago, an event run with the chicane at the end of the lap in place.

Continuing the promising pace shown in Miami and Monaco, Alpine was well-represented in the early running.

Gasly held down second fastest behind Verstappen, his time 0.4s slower but encouragingly set on the same compound rubber.

Like Verstappen, Lando Norris wasn’t happy with his initial set-up, reporting porpoising and bottoming approaching the final corner which was “upsetting the car quite a lot”.

The McLaren driver sat 11th midway through the hour-long hit out,

At that point, Red Bull sent its pairing out on a set of soft rubber, Perez having improved to sit second fastest with a 1:15.374s.

Verstappen had moved the pace on to 1:14.606s, more than five seconds faster than the same session last year.

The soft tyre runs confused the timesheets, with Zhou Guanyu and Valtteri Bottas sitting third and fourth respectively with just under 20 minutes remaining.

Mercedes, meanwhile, had both its cars at the foot of the timesheets; George Russell slowest of all at 1:18.468s and Lewis Hamilton only 0.3s better.

Both had been prolific in terms of laps, the team having introduced two new components, a new sidepod inlet and diffuser, for the Spanish GP.

It was only inside the final 10 minutes that Russell headed back out, a set of softs fitted to his W14.

It resulted in him vaulting to eighth, though still 1.1s off the pace.

Hamilton was out soon after, also on a set of soft tyres, managing a 1:15.845s to slot in just 12th fastest.

Verstappen remained quickest, the only driver into the 1:14 bracket as he sat comfortably clear of the rest of the pack.

As the chequered flag waved, Perez was second best while Alpine enjoyed an enormously positive start to the weekend with Esteban Ocon third and Gasly fifth – split by Nyck de Vries.

Behind them was Fernando Alonso, Kevin Magnussen, Leclerc, Sainz, Russell, and Norris as the leading McLaren.

Oscar Piastri was 17th, his best a 1:16.353s, about 0.6s away from his team-mate.

Practice continues with Free Practice 2 at 17:00 local time (01:00 AEST).