George Russell sets the initial pace in Bahrain as the FIA trials a revised starting procedure.

21 of this season's drivers were on duty today as testing resumed in Bahrain, the only driver not making an appearance being four-time world champion Max Verstappen, who is scheduled to run tomorrow.

Between them the drivers completed 1,156 laps, the second fewest since the first day of testing last Wednesday. Pace-setter Russell completed the most (76), ahead of Arvid Lindblad (75) and Valtteri Bottas (71), while Sergio Perez (24) completed the fewest. Mercedes (145) was the team with the most laps under its belt, ahead of Racing Bulls (136) and McLaren (124), while Red Bull completed just 66, Cadillac 59 and Aston Martin 54.

Like last week we saw lock-ups and offs aplenty, however there was only one red flag over the course of the day, Lance Stroll going off at Turn 11 an hour into the afternoon after his rears locked in what some saw as a gearbox related issue.

We saw lots of drivers trying to see how close they can follow rivals under the new regs, with Kimi Antonelli pulling off one of the best moves of the day when he nailed Alex Albon in Turn 13.

As ever, the start of the day saw the aero sensors in use, while flo-vis was in evidence throughout the session, Ferrari, in particular using it right up until the chequered flag.

Cadillac lost time with a sensor issue this morning, while the Red Bull crew formed a wall to prevent prying eyes and cameras seeing what was wrong with Hadjar's car.

Over an hour before the lunch break Fernando Alonso was in his civvies as Aston Martin's problems continue. The Spaniard completed just 28 laps, and with Stroll only adding a further 26 this afternoon it is understandable why the Silverstone-based outfit's crew are looking so glum.

Of interest is the Aston Martin's high rake angle, and while this is a characteristic of Adrian Newey's cars, this time it even more noticeable. Also attracting interest was a 'mini wing' in front of the exhaust pipe on the Ferrari, said to be for aiding downforce and stability.

At a time the Mercedes-powered drivers insist that Red Bull is the benchmark Laurent Mekies was having none of it.

"We very well know the size of the competition, we very well know the size of the mountain that is still in front of us, we just had a very good start at it," said the Frenchman. "We know we are going to run into a number of uncomfortable moments where the gap to the competition will be too big, where the car will stop on track or will not get out of the garage like this morning, unfortunately, where we got an issue with Isaac.

"It's part of the game," he continued, "but we are happy to be in the game and it's going to be a huge mountain from now on. The performance shown by the top guys is stratospheric and it's going to be a huge development race, chassis side, PU side, but it's what we all love."

Indeed, while Mercedes led the way in terms of pace and the number of laps, Hadjar only completed 66 laps and was almost a second off the pace.

A number of drivers were asked about McLaren's concern at safety during starts.

"It's definitely not dangerous," insisted Lewis Hamilton. "I think we should probably take that connotation away from it, because it's just a different procedure.

"It's just a longer procedure than it has been in the past," he added. "If right now you put the five lights up, we would all still be standing there when the lights went out for a little bit longer. But you can still pull away without the turbo going. It's just that you probably will anti-stall a couple of times. So perhaps the anti-stall is something that maybe is a potential for some people. But I don't think that it's dangerous."

"Honestly, I don't think it's more dangerous than before," agreed Valtteri Bottas. "The main difference is with holding revs for longer. And I think we've got to figure out something for that, because my only concern with that is like when you're at the back of the grid, the light will already start going and you won't have enough time to get the turbo spinning before the lights go off.

"That's obviously only an issue for the drivers in the back," admitted the Finn. "But apart from that, I think we'll find solutions, and I don't see any element of danger in just having to hold revs for longer."

As was the case this morning and last week, the evening session ended with Race Control tests, however following today's F1 Commission meeting, a new start procedure was trialled.

Only ten drivers took part, Stroll being the only no show, as ten minutes from the end the session was red-flagged. All the cars headed back to the pitlane before - once the pitlane opened - heading out again and returning to the grid.

Following an extra formation lap the cars once again took their place on the grid - leaving an empty row in front, just in case - before the grid panels flashed blue for five (extra) seconds, after which the standard start light procedure followed.

All went smoothly, with no incidents and no one left behind, though all ten were very, very cautious through Turn 1.

Worth noting, and something that hasn't really been covered yet, is that only a week after Melbourne comes Shanghai, and that's a Sprint weekend with just the one practice session. So, while everyone is salivating over potential fireworks in Oz, it could be China where we really witness some genuine mayhem.

Kimi Antonelli was in the Mercedes for the morning session with Russell taking over for the afternoon. The Italian completed 69 laps around the Bahrain International Circuit as the team focused on evaluating several updates brought to the track. Russell completed a similar programme later in the day, finishing with a total of 78 laps and topping the timing screens with a 1:33.459. The Briton will continue in the car tomorrow before Antonelli takes over for the afternoon.

"We enjoyed a positive morning and overall, a good day to begin this second pre-season test," said Antonelli. "We had an extensive programme planned with plenty of items we wanted to test. We managed to work through that list efficiently with few delays and learnt a lot more about the W17.

"Whilst we've had a solid start to these final three days of running ahead of Melbourne, there is still lots of work for us to do in these final days. Several of our competitors continue to look strong and we have to continue to evolve our package and find more performance. Australia is not far away now so we will be working hard to maximise these final two days here in Bahrain."

"It was good to get back on track," added Russell. "With only three days of pre-season running left before we head to Melbourne, every lap is precious. We didn't enjoy the best reliability in the first test, but we've started off on the front foot this week, completing 147 laps between myself and Kimi.

"We have brought several updates to the W17 this week, so our programme was focused on evaluating those and ensuring we didn't encounter any nasty surprises. We were able to complete most of the work we had planned and can now continue to build our learning over the final two days of running."

"We have made a solid start," said Andrew Shovlin. "We've updated a few parts on the W17, and they seem to be doing what we hoped. We've also been working through a programme of set-up items trying to understand more about the car and tyres. The track changes quite considerably over the course of a day here as it heats up and cools down so it's often difficult to analyse results, but we seem to have been able to keep the car in a good window and it's been encouraging to see that degradation has been under control.

"We've still got a lot of work to do as we go into the final two days so fingers crossed the W17 will continue to run reliably and allow us to get through our full programme."

Check out our Wednesday gallery, here.