If today was about halos and race simulations for some, it was a red flag day - as opposed to red letter - for Romain Grosjean and Haas.

Following a couple of days when the American outfit's mileage resembled that of McLaren twelve months ago, things finally looked to be sorted.

At the end of another long night for the Banbury boys, Grosjean followed Kimi Raikkonen down the pitlane to get the penultimate day of testing underway. After a few tentative installation laps the Frenchman finally posted a time, then improved it.

Then, in the moments before lunch, following reports from the team that it was suffering a "transmitter issue", out came the red flag for the first time as Grosjean went into the gravel at T5. Initial reports that he had clouted the barriers proved incorrect, but the Frenchman was at a loss to explain why he had gone off.

An hour after the break and he was off again, this time at T1, the Haas seemingly having spun and gone into the gravel sideways. The Frenchman - who was still unsure of the cause of his first off - looked at the back of the car, clearly perplexed.

Finally, around eight minutes before the end of the session, Grosjean pulled to the side of the track at T10, bringing out the red flag for the third time. This at a time when nine other drivers were still on track running their respective programmes.

Whatever the issue(s), it is clear that Haas has a lot of work to do, and little time in which to do it.

Elsewhere, Raikkonen dominated the timesheets and the headlines, the Finn being the first driver to publicly run with the new halo safety device - or at least Ferrari's version of it.

Hands up all those who never thought they'd hear the words Raikkonen and halo mentioned in the same sentence.

It was a good day for the Finn, who completed 136 trouble-free laps on his way to posting the best time of the test thus far.

As unflappable as ever, when Grosjean caused his second red flag, the Ferrari driver, who was on a race simulation, calmly pitted and continued when the lights went green again.

At one stage on his race sim, which saw him on a soft, medium, medium, hard strategy, the Finn was challenged by Pascal Wehrlein who was on a qualifying simulation, whilst later in his 'race' he was left for dust by Hamilton.

A good day for Williams also, Felipe Massa completing 119 laps en route to posting a best time just 0.428s off Raikkonen's pace, but on the soft rubber as opposed to the ultrasoft.

Another strong day for Force India and Toro Rosso, where drivers Nico Hulkenberg and Max Verstappen completed 137 and 159 laps respectively. That said, their best times were on the ultrasoft.

Yet again, Mercedes split driving duties, Rosberg in the morning and Hamilton this afternoon. No dramas from either driver, just lots and lots and lots of laps.

After yesterday's disappointment it was an altogether better day for Sauber, Felipe Nasr completing 116 laps, one of seven drivers to exceed the ton.

Fernando Alonso finished the day seventh, 2.1s off Raikkonen's pace, the Spaniard's best time set on the supersofts. Indeed, when he tried the ultras he couldn't find more pace.

Indeed, subsequently a race simulation appeared to be aborted, the Spaniard having adopted an entirely different (tyre) strategy to what others were running, having started on the hard rubber.

Interestingly, during the lunch break McLaren appeared to have a large number of crates arrive, possibly the first of a number of updates the team has promised.

Though Wehrlein spent a lot more waiting around in his garage than he probably wanted, the German did get to post a fairly respectable time 2.148s off Raikkonen's, albeit on the ultras.

That said, whilst the rookie finished ahead of Kvyat, Palmer and Hamilton, one cannot help but feel that we were expecting more from the Mercedes-powered, Williams-aided team. Or are we expecting too much, too soon?

At Red Bull, Daniil Kvyat mirrored teammate Daniel Ricciardo's programme from yesterday, lots of pit stops in the morning and a race sim in the afternoon.

Indeed, it's worth pointing out that today the twelve drivers on duty exceeded yesterday's mileage.

Jolyon Palmer only just missed out on one hundred laps, the Briton appearing to suffer the issues that teammate Kevin Magnussen avoids.

With just one day remaining before the teams pack up and start heading to Melbourne, for many today was their last time in their cars until Oz.

After seven days of testing there are, as Johnny Nash once sang, more questions than answers... among them, what is the true pace of the Mercedes, likewise the Williams, is the Ferrari going to be bulletproof and what exactly is wrong at Haas?

"It was one of our best days of testing," said Raikkonen, whose day was devoted to aero and set-up testing, tyre testing and a race simulation. "We could run without a single stop, except for the red flags on track.

"Maybe we could have been faster on some laps, but in general the feeling was fine and we are more or less happy with the way things are going. Of course there's always room to improve and work to do.

"Like I said many times, I don't like guessing so there's no point in figuring out where we'll be in Melbourne. We will try our best as always. This morning I tried the Halo protection device and the difference to the usual driving was surprisingly small. The visibility is just a little bit limited at the front but I don't think this is the final version of the device, so it can be improved further."

"Today has been a very positive day," said Felipe Massa. "We managed to do our programme without any problems, which included some long runs and also some short runs. We tried the soft and even ultrasoft tyres. Unfortunately I couldn't do my ultrasoft lap because we had some traffic, but overall it was a very good day and good to understand the car in a better way.

"I am definitely much happier this week compared to last week," he admitted. "We are almost ready for the first race, which is really when we will have a proper idea of where we are compared to the others, but today was a good day.

"It's been another productive day for us," added the Grove team's Chief Test & Support Engineer, Rod Nelson. "We started off with some suspension and tyre tests this morning when the conditions were more stable, as usual here in Barcelona. Over the lunchbreak we did a grid process simulation, and then a first race stint straight after. We've also completed a qualifying simulation running on mediums, softs, and ultrasofts at the end.

"Sadly, Felipe couldn't set his potentially quickest time on the ultrasofts due to traffic, so he was actually quickest on a soft tyre.

"We also did some more system work and aero evaluations, so a bit of everything really. We'll spend a few days following the tests looking at all the data but I think we can be reasonably positive that we are up there at the sharp end. Exactly where we are we will only really know after the first few races of the season though.

"In terms of development, Felipe and Valtteri are both giving similar feedback. They are sensitive to different aspects of car performance, but they broadly agree with each other's comments, which really helps. They push each other on sportingly and technically, so are a good combination."

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