Hamilton fastest, Bottas 2nd, Raikkonen 3rd, Vettel 4th
Hamilton fastest in first practice
Alonso breaks down after three corners, then leaves circuit
Teams bring upgrades for fifth race of the season
Mercedes back stronger than ever? Their showing in Friday practice suggests that to be the case but it is from tomorrow when it really matters.
That's about it from us. Pop on over here to read Andrew Benson's take on how today went and join us again tomorrow at 09:30 BST.
Until then, cheerio.
Image source, EPAJosephat Okora: Ferrari have not turned up yet. Tomorrow will be very important for them.
Tom Clarkson
BBC Radio 5 live commentator
What's significant is Mercedes' pace on the long runs. They have the qualifying pace but Ferrari have had the advantage over the long runs but Mercedes appear to have leapfrogged them from what we have seen today.
11) Grosjean 12) Ocon 13) Vandoorne 14) Perez 15) Magnussen 16) Ericsson 17) Stroll 18) Kvyat 19) Wehrlein 20) Alonso
1) Hamilton 2) Bottas 3) Raikkonen 4) Vettel 5) Verstappen 6) Ricciardo 7) Hulkenberg 8) Palmer 9) Massa 10) Sainz
Lewis Hamilton finishes quickest in second practice for the Spanish Grand Prix.
Valtteri Bottas cuts up his tyres as he runs wide at Turn 7. He skips across the gravel before rejoining the track.
Two minutes to, it's going be Lewis Hamilton fastest again.
Jeremiah Kariuki: On race simulation, Mercedes seem to have an edge too! Looks like their dominance could be felt in Spain!
Andrew Benson
Chief F1 writer in Barcelona
Image source, Getty ImagesMercedes have been pounding round. They are lapping consistently quicker than anyone else.
Just realised, I have not heard Romain Grosjean complain once today. Is that a first this season?
Things seem to be going OK for the Frenchman in the Haas. He's 11th quickest and has done 30 laps so far in second practice.
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
Frankie Muniz, of Malcolm in the Middle fame, is at the circuit and fully engrossed in one of the new initiatives brought in by F1's new owners - live demonstrations of what happens in a team garage.
Ten minutes to go.
Fernando Alonso heads back to the pits. No improvement and he remains bottom of the pile with 17 minutes to go.
Meanwhile, a problem for Max Verstappen in the Red Bull.
"The car doesn't turn any more," he says.
Quite the problem on a track that has 16 corners...
Steven: Is it even possible for the engine to be any slower?
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
Or maybe not.
"The engine feels slower than before," says Fernando Alonso. "Amazing."