Postpublished at 13:11 British Summer Time 12 May 2017
And Sebastian Vettel goes quickest of all with 1:23.143.
Daniil Kvyat is not happy with how his Toro Rosso is handling. "I'm coming in," he says. "Something feels wrong at the front."
Summary
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
Postpublished at 13:11 British Summer Time 12 May 2017
Postpublished at 13:09 British Summer Time 12 May 2017
Sergio Perez puts in a more competitive time with 1:25.033 to go top of the order. None of the big hitters have put in a time yet. Sebastian Vettel is on the circuit but Lewis Hamilton and Valtteri Bottas are staying in the Mercedes garage for now.
Everyone is out on mediums at the moment but its when the softs are bolted on that we'll start to get an idea of the order here.
Postpublished at 13:06 British Summer Time 12 May 2017
A tentative start to proceedings by Kevin Magnussen, who does a 1:31 in the Haas.
A problem cut short his first practice and he's still not comfortable with things this afternoon.
"The rear is nowhere," he reports.
Postpublished at 13:04 British Summer Time 12 May 2017
Image source, .There's been 10 different winners in each of the last 10 Spanish GPs. Can you remember who won what year? Head here to have a go at our quiz.
It's pretty straightforward but you also get a picture of 1980s Arnold Schwarzenegger, so well worth the journey.
Where's Fernando?published at 13:02 British Summer Time 12 May 2017
Jennie Gow
BBC Radio 5 live pit-lane reporterFernando Alonso is not in the garage yet. His car is still up on the stands although in fairness so is Stoffel Vandoorne's.
Postpublished at 13:01 British Summer Time 12 May 2017
Go! Go! Go!published at 13:01 British Summer Time 12 May 2017
There's a few clouds in the sky but otherwise it is a lovely, lovely day in Barcelona.
Second practice is under way with Kevin Magnussen first out on the track.
Postpublished at 12:59 British Summer Time 12 May 2017
Timo's on his waypublished at 12:59 British Summer Time 12 May 2017
Postpublished at 12:59 British Summer Time 12 May 2017
Jolyon Palmer is back in the Renault this afternoon after letting Sergey Sirotkin take the wheel this morning. The Briton is just getting strapped into his car at the moment.
Postpublished at 12:57 British Summer Time 12 May 2017
The fans have been kept entertained at the circuit today - not quite sure what's going on here...
Image source, Getty Images...while these two don't seem to have bought quite enough Ferrari branded merchandise.
Image source, Getty ImagesGet involved #bbcf1published at 12:55 British Summer Time 12 May 2017
Will Fernando Alonso get to the end of second practice? Or will those cheeky technical gremlins come out to play once again?
For a bit of fun, how about playing Alonso breakdown bingo. How many laps do you think he will manage and what do you expect we will hear from him on the radio?
This morning Alonso went to play tennis to make up for missing out on track time, any other's suggestions for how Fernando could fill a Friday?
Get involved via #bbcf1, text in on 81111 (UK only) or post a comment on the BBC Sport Facebook page.
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End of instagram postPostpublished at 12:50 British Summer Time 12 May 2017
BBC Radio 5 live commentary is online only for second practice. Tune in via this page from 12:55 BST.
You might get more travel tips from Andrew Benson as well.
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Postpublished at 12:48 British Summer Time 12 May 2017
Image source, Getty ImagesIs that Daniel Ricciardo riding a honey badger?
Note another sad face Fernando Alonso in the distance. This time as a mosaic.
And here's Nico Hulkenberg as The Hulk, naturally.
Image source, Getty ImagesPostpublished at 12:46 British Summer Time 12 May 2017
Image source, Getty ImagesAmazing.
Postpublished at 12:45 British Summer Time 12 May 2017
Image source, Getty ImagesThe other news from first practice was that it was business as usual involving the front runners. Lewis Hamilton was quickest ahead of his Mercedes team-mate Valtteri Bottas with Kimi Raikkonen and Sebastian Vettel third and fourth respectively for Ferrari.
Plenty of us are keeping our fingers and toes crossed that this is the race Red Bull finally join the party but that's not looked the case so far. Max Verstappen, who was fifth quickest, was more than a second off Hamilton's pace.
Early days, though.
Alonso's back!published at 12:39 British Summer Time 12 May 2017
The good news is Fernando Alonso is back for second practice, which gets under way at 13:00 BST.
He posted this image of him back at the track on Instragram along with the message: "1:15h training to compensate the lack of laps this morning and be fit for FP2. Ready."
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End of instagram postPostpublished at 12:36 British Summer Time 12 May 2017
Another day, another McLaren break down.
Fernando Alonso just about managed to get to the third corner in this morning's first practice before his car came to a stop, ending his session. He had no intention of sitting about watching the others having fun on the track so went off to play tennis. As you do.
Even this Alonso tattoo looks sad about the Spaniard's predicament.
Image source, EPAAnywhere but herepublished at 12:30 British Summer Time 12 May 2017
Image source, Getty ImagesIt's been that kinda day for Fernando Alonso...
Postpublished at 10:44 British Summer Time 12 May 2017
Not much to read into first practice with plenty of questions left unanswered - will it be a fight between Mercedes and Ferrari again? Have Red Bull closed the gap? Will Fernando Alonso return or just sack it all off to play tennis?
Find out when second practice gets under way at 13:00 BST and join us for build up from 12:30. See you then.