Nico Rosberg goes top of the pile with a 1L15.181, 0.027s quicker than Sebastian Vettel.

Just under 20 minutes into the session and the top 10 looks like this:

1) Rosberg 2) Vettel 3) Perez 4) Kvyat 5) Hulkenberg 6) Hamilton 7) Raikkonen 8) Gutierrez 9) Sainz 10) Grosjean

Andrew Benson
Chief F1 writer in Monaco

Image source, Getty Images

Friday is rest day in Monaco and Jenson Button spent much of the afternoon sunning himself on his boat in Cap d’Ail harbour, just around the corner from his house in Fontvieille. But will he have his day in the sun in qualifying? 

McLaren came to Monaco with even Button predicting they should be the fourth fastest team, but it did not look that way on Thursday, with Button 10th, behind two Toro Rossos and a Force India as well as the usual big three, and Fernando Alonso only 12th, admittedly after not getting in a qualifying simulation run. Afterwards, Button did not sound quite so optimistic about their chances. ‘There are cars more competitive than we thought,’ he said. ‘The STRs are pretty quick.’

No times yet from either of the McLarens. Ron Dennis has put the pressure on his drivers by saying the team will be the one to knock Mercedes off their perch first, but they haven't exactly set the world alight in Monaco.

Plenty of timed laps being completed now. Mercedes have had a spell at the top with Lewis Hamilton (1:15.433) ahead of Nico Rosberg (1:15.466), but Sebastian Vettel then goes quickest of all with a 1:15.208.

No sign of either Red Bull yet.

Yellow flagpublished at 10:12 British Summer Time 28 May 2016

10:12 BST 28 May 2016

A spin for Jolyon Palmer! He loses the rear of his Renault coming through the chicane, tags the wall and damages his rear wing. The Briton rights himself and gets his car back to the pits. Not an ideal start to the session for the rookie.

Image source, Getty Images

The breaking news this morning was that the 'halo' driver head protection device will be introduced in 2017. What's your thoughts? Let us know via #bbcf1

Jason Smith: Agree with the idea and the concept! Absolutely hate the Halo design, much prefer the Aero screen idea...  

Philip Stone: 1st stage of a cockpit .  

Andrew Benson
Chief F1 writer in Monaco

Much was made before Monaco of the debut of the new Pirelli ultra-soft tyre, the idea behind it to give a new, softer, grippier tyre after complaints that the tyres have been too hard for this gentle track surface in recent years - hence the plethora of one-stop races. But the ultra-soft was underwhelming. Lewis Hamilton said: "For me at the moment, it feels exactly the same as the super-soft, just a different colour."

Kimi Raikkonen, Kevin Magnussen and Jolyon Palmer are all out on the purple-walled ultra soft tyres. Palmer briefly goes quickest with a 1:18.700 but his stay in P1 is brief as Raikkonen clocks a 1:16.220.

Romain Grosjean and Kimi Raikkonen follow Esteban Gutierrez out. 

Ferrari had, as Sebastian Vettel described it, a scrappy day on Thursday. They never really showed their true pace, while Vettel struggled for grip. 

They need to start flexing their muscles soon after a fairly uninspiring start to the season.

The light goes green at the end of the pit lane and Esteban Gutierrez, like he was on Thursday, is the first to head out onto the track.

Andrew Benson
Chief F1 writer in Monaco

Formula 1 is to introduce the ‘halo’ driver head protection device in 2017.

Technical chiefs have decided the device, which forms a protective structure in front of and above the driver’s head, is the more ready of the two alternative options.

But work will continue on the ‘aeroscreen’ championed by Red Bull with a view to introducing it in 2018.

A modified version of the ‘halo’, which was first run by Ferrari pre-season, will be tested in June ahead of planned final agreement in July.

Image source, Getty Images

With practice on Thursday in Monaco, the drivers had a bit of time away from the car yesterday. 

Many of the drivers suited up for the Amber Lounge Fashion Show, while a few celebrities turned up to mingle with the teams. Here's Manchester United midfielder Michael Carrick at Red Bull.

Image source, Getty Images

BBC Radio 5 Live

Image source, bbc

Right then, let's crack on with a bit of housekeeping so you know what's coming up, when it's coming up and how you can follow it.

One hour of final practice gets under way at 10:00 BST, with qualifying starting at 13:00. You will be able to listen to commentary from Jack Nicholls and company online, with qualifying also on BBC Radio 5 live.

The drivers are allowed to have a tinker with their helmet designs this weekend. Why? Because it's Monaco. This is Daniel Ricciardo's effort.

What would your F1 lid look like? Feel free to ping over your own designs to #bbcf1, external

Can you see Red Bull upsetting the apple cart this weekend? Let us know via #bbcf1, text in on 81111 (UK only) or post a comment on the BBC Sport Facebook page.

Andrew Benson
Chief F1 writer in Monaco

Lewis Hamilton and Daniel Ricciardo were the two stand-out stars of Thursday practice. 

Hamilton put in a virtuoso performance in the first session, on a separate level from team-mate Nico Rosberg for the first half-hour of the session, seconds faster as he went right out to the limit much sooner than the German. 

And in the second session, Ricciardo was also scintillating - 0.6secs quicker than the Mercedes in the only Red Bull with the new, upgraded Renault engine, and 0.9secs quicker than team-mate Max Verstappen, when the extra power was not even worth a quarter of that around Monaco. Brilliant.

Andrew Benson
Chief F1 writer in Monaco

Image source, PA

Sitting on a boat in the harbour on Thursday evening, Nico Rosberg was extolling the virtue of having extra day to prepare for qualifying in Monaco. 

Red Bull, he said, were simply faster than Mercedes in Thursday afternoon practice and the team needed the extra time to go through the data to work out what they were doing wrong. Executive director (technical) Paddy Lowe said he expected the tyres were the root of it, Mercedes having not run the new ultra-soft tyre before taking to the track on Thursday. 

Can Mercedes get on top of it? Do the silver cars face a genuine challenge here? This final practice session will provide vital clues.