Red Bull were optimistic of getting Daniel Ricciardo back out on the circuit, but he still has just the two laps under his belt so far. Time's running out - 12 minutes remaining.

Just three drivers are out on the circuit - Carlos Sainz, Susie Wolff and Felipe Nasr. Wolff improves from 17th to 10th with a 1:29.708 and is within a second of Felipe Massa.

Meanwhile, a couple of late tweaks to Sebastian Vettel's Ferrari and Fernando Alonso's McLaren as they have a new front wing and new rear wing fitted respectively.

Nico Rosberg could be in a bit of bother. A few moments ago he made a late decision to enter the pits, heading in outside of the designated entry zone. Stewards confirm he is under investigation as a result.

Gareth: I'm a '90s child so the MTV Simtek was a big fave of mine. RIP Roland Ratzenberger.

Image source, Getty Images

Paul Young: What about the Buzzin Hornets!? Very bold and striking. Jordan at their Zenith!

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The temperatures are climbing as midday approaches. Track temperature is now 33C, with air temperature currently 24C. It is all getting a bit too toasty for Kimi Raikkonen as he complains of a hot seat. He's currently fourth fastest in the Ferrari.

Lee McKenzie
BBC F1 pit-lane reporter

"Susie Wolff is getting back in the car. In terms of fitness she is in her prime - she has been to Kitzbuhel where ski-ers train."

Image source, Formula 1

There's been a couple of changes to the circuit ahead of this weekend's race, with CCTV cameras installed at the exit of Turn 3, where Fernando Alonso had his pre-season accident.

The openings at Turn 4 have been enlarged to allow better access for tractors, while other changes include modified kerbs at Turn 9 and a new kerb on the exit to Turn 15.

Image source, Getty Images

This is, of course, the circuit where Fernando Alonso crashed in February, resulting in him missing the season opener in Australia because of concussion.

Despite what happened, Alonso has no concerns about taking to the circuit again, saying: "It is an accident that happened three months ago.

"Unfortunately it was a little bit longer to recover and the impact was a little bit unlucky and it put me out of the car for one month. I'm coming back here with full confidence and full motivation to deliver a good result in front of a home crowd."

Image source, McLaren

McLaren:, external A few speedy tweaks for Fernando Alonso then back out on track. 25 minutes of FP1 remaining.

Lewis Hamilton nudges his team-mate Nico Rosberg out of P1 with 1:26.898 but it is a brief stay at the top as Rosberg improves again with a 1:26.828.

Image source, Lotus

After impressing in practice run outs for the Chinese and Bahrain GPs, Jolyon Palmer is back in the Lotus again today. He returns to the circuit, looking to improve on his current best of 1:30.207, the 14th fastest time.

Half the field are out on the circuit at the moment.

Fernando Alonso, winner of his home race in 2006 and 2013, is up to seventh with 1:29.813 as more cars head back out on to the circuit for the last half hour of the session.

ATMartin: Mika Hakkinen's MP4-13, 1998!

Image source, Getty Images

Bora Yazkan: It's so simple, no big sponsorship logos and the most important... it's fast!

Image source, Getty Images

This little beauty is Button's 2009 Brawn.

Andrew Benson
Chief F1 writer

Image source, Caterham

"A little human interest story about Manor's Will Stevens. The Englishman had his eye on the auction of the assets of the now-defunct Caterham team, for whom he made his grand prix debut in Abu Dhabi last season. He considered buying the steering wheel from that car.

"'I actually thought it would be nice to have my steering wheel from my first grand prix,' he said. 'I haven't put a bid in but I spent some time there and if there was anything I wanted it to keep it would have been the wheel from my first grand prix. I didn't look into it too much and I don't know how much it would go for but, just talking about it, we said if we could have something to look back on in the future it would be the steering wheel.'"

Image source, Formula 1

Daniil Kvyat has spent a bit of time during this lull in circuit activity chatting away with Red Bull motorsport consultant Helmut Marko. The Russian has been running with the new short nose in this session.

Meanwhile, Will Stevens has strapped his helmet back on and dived into the Marussia to break the silence and roll back out on to the circuit, closely followed by Fernando Alonso.

Andrew Benson
Chief F1 writer in Barcelona

"There has been further bad news for Force India this weekend, with the revelation that the much-vaunted 'B-spec' car they initially expected for this race has been delayed - again. First it was put back to Austria in June. Now, it turns out it will not be ready until the following race in Silverstone.

"Sergio Perez admitted this was not ideal, and said Force India - after a step forward at point-and-squirt Bahrain - would struggle in Spain this weekend.

"'This race will be particularly difficult,' the Mexican said, 'considering what this track is like regarding downforce as this is where we are lacking the most. We do not have any upgrades but some of the other teams are bringing upgrades. But we have done an amazing job to be just one point from Lotus and 12 points from Red Bull. It's a good effort from the team so when the upgrade comes, we should be in a strong position to fight back and challenge them.'"

Image source, Getty Images

This weekend marks 25 years of the Circuit de Catalunya hosting the Spanish Grand Prix so to recognise that fact, we'll have a little gander at some of the track's most memorable races and moments.

A natural place to kick things off is with the first race to be held on the circuit - the 1991 Spanish GP.

Nigel Mansell came out on top of an early, sparks-filled tussle with Ayrton Senna before going on to win, and we've delved into the archives to provide you with highlights of the race, replete with a cracking old school BBC Sport logo and The Chain-infused intro.

Image source, Getty Images

Ian Watson: I may be biased but the Williams '92 car with our Nige Red 5 has always been my fave.

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Salim: Minardi M02, even though it wasn't perhaps the best performing, it was definitely striking!

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