As pre-season testing finally gets underway, gearshift problem for Mercedes leaves Valtteri Bottas with just 6 laps to his credit.

Veteran Kimi Raikkonen had the honour of being first on track this morning, though Sebastian Vettel and Daniel Ricciardo were hard on his heels.

With the air temperature a balmy 30 degrees C, and the track standing at 36 degrees, the only worry was the wind which was clearly picking up.

As one would expect on the first day of the test, which was preceded by Haas unveiling its new car and all the drivers gathering on the grid with their cars for the now customary photo-op, aero rakes and flo-vis were very much the order of the day, with AlphaTauri appearing to sport the biggest.

Charles Leclerc was the first driver to post a time, just moments before Valtteri Bottas and Roy Nissany finally took to the track.

Vettel subsequently went quicker than his former teammate, albeit on softs as opposed to Leclerc's hards.

In time Raikkonen went top, but it was clear the Finn was struggling with the Alfa Romeo, though in all honesty it is not so clear whether this was down to the car or the increasing wind.

Just 45 minutes into the session the screens went up outside the Mercedes garage, and with this action having been outlawed last year it was obvious the German team had a problem.

As Lewis Hamilton watched proceedings, the world champions revealed that a gear shift issue necessitated a gearbox change.

A minor spin for Max Verstappen was a portent of things to come, the Dutchman running wide on a number of occasions during the course of the morning, but again it was unclear if this was down to the wind or the car.

As Gasly, Ocon and Ricciardo each posted respectable times, Haas reported a hydraulics issue for Mick Schumacher, the American team subsequently following Mercedes example and opting for a change of gearbox.

As Ricciardo went quickest, Nissany appeared, his Williams sporting a large aero rake, while the timing screens suggested that Raikkonen had posted a 1:12, around 19s quicker than anything witnessed over the preceding two hours... or any time before.

Leclerc was the first to try the prototype tyres that Pirelli has here, while later in the session Vettel also tried them.

Each team has 30 sets of slick tyres for the test. On top of that, each team also has two sets of intermediates and wets available: but these will only be counted within the allocation of 30 if they are fitted. No more than 30 sets of tyres per team are allowed to be used throughout the three days.

However, there will be two extra sets of prototype tyres supplied to each team: identical in every way to the standard C3 but produced in Turkey rather than Romania. These are being run simply to benchmark products from the back-up factory against the standard tyres, both during performance and longer runs. They can be recognised as they are plain black, with no markings at all.

With around 90 minutes remaining, the wind was increasing and now sand was being blown on to the track, with talk of a possible sandstorm about to hit the venue, all of which caused further problems for those drivers already struggling.

When Vettel stopped at the end of the pitlane and was unable to get going again, his crew ran to his rescue... not the easiest of tasks in such heat. The Silverstone-based outfit subsequently described the problem as "minor" and the German was soon back on track again.

With just over half-an-hour remaining, Bottas finally headed out, the Finn posting an exploratory 36.850, over 4s off Ricciardo's best.

Schumacher finally got back out with around 20 minute remaining, by which time Gasly, Raikkonen and Verstappen had all completed the equivalent of a race distance.

The morning session was brought to an early close when Leclerc stopped on track (Turn 4), his Ferrari clearly heard to have been misfiring just moments before.

Following a brief red flag period the session resumed under the VSC just moments before the lunch break.

While some will focus on Mercedes problem let's not forget that this isn't the first time the German team has encountered pre-season issues. Nonetheless, mileage is king, and while McLaren had the pace this morning, AlphaTauri had the reliability, ahead of Alfa Romeo and Red Bull.

Check out our Day 1 pre-season test gallery from Bahrain, here.