To paraphrase William Shakespeare, "BS, or not BS, that is the question."

In Spain, and again on Thursday this week, Lewis Hamilton insisted that Ferrari has the advantage, the Briton strenuously backing up his claim by saying it wasn't "BS".

However, while in Spain he closed to within 0.010s of Sebastian Vettel's best time, yesterday he was 0.8s quicker, with even the Red Bull duo ahead of the Ferraris.

While all should become clear(er) in the final stages of this session, and in Q2 and Q3 that follow, one thing is clear, Mercedes is not on the back foot.

Other than the fact that we wait to see if Honda is providing a 'party mode' for Red Bull, one worrying factor yesterday was the length of time it took Ferrari to react following FP2, suggesting that the Italian team was caught off guard by Mercedes pace.

Certainly, Ferrari has much work to do.

As for that crazy, crazy melting pot that is the midfield, Alfa is clearly the most improved team, while Williams has actually taken a step backwards on last year.

Very early days, but on yesterday's form, Alfa and Renault appear to be the midfield pace-setters, ahead of Haas, with Toro Rosso, McLaren and Racing Point right behind.

Interestingly, while both Ferrari drivers were not entirely happy with their "wobbly" SF90s, not helped by blustery winds and Melbourne's notorious bumps, it is Verstappen who has been given a new chassis for today's sessions after an issue was discovered with the fuel cell late last night.

Ahead of the session, the air temperature is 22 degrees C, while the track temperature is 42 degrees. Like yesterday, it is bright and sunny.

The lights go green and Verstappen is first out, no doubt wanting to do an install lap with that new chassis.

Meanwhile, due to an oil leak on Grosjean's car, Haas was forced to break the curfew last night.

Raikkonen heads out, followed by Magnussen, Albon, Sainz and Kvyat.

More drivers head out, a fair mixture of all three compounds.

The Williams pair post the first times of the day, Russell 30.332 and Kubica 45.881, the Pole having almost tangled with Norris in the pitlane when the pair were both released at the same time, the McLaren driver having to hit the brakes... hard.

"I'm sliding all over the place," reports Russell.

The pair soon improve to 29.310 (Kubica) and 30.332. Both are on the mediums.

While the Williams duo continue to shave fractions off their times, Gasly becomes the third driver to join the timesheet, the Frenchman's 26.159 almost 3s ahead of Russell.

Moments later, Verstappen posts 25.106, leaving the Williams pair over 4s in his wake. Both Bulls drivers on mediums.

The stewards are investigating that pitlane incident involving Kubica and Norris.

Fifteen minutes in and the Ferraris, Mercedes and Racing Points have yet to appear.

As Ricciardo begins his first flying lap, former teammate Verstappen improves to 24.944.

Sainz goes third with a 26.222, but is demoted when Ricciardo goes second, despite running wide in the final corner, with a 25.216. The Australian and Spaniard on the softs.

A 24.860 sees Kvyat go quickest on the softs, with teammate Albon posting 25.098 to go third.

Grosjean goes second on the softs, as the Ferrari pair and Bottas finally head out, leaving Hamilton as the only no-show. Those three are all on the softs.

Going quickest of all in S3, Magnussen crosses the line at 24.884 to go third as Hulkenberg goes fifth and Raikkonen ninth.

Bottas and Vettel trade fastest sector times, the German finally crossing the line at 23.739 while the Finn posts 23.853. Leclerc goes third with a 24.564.

As Hamilton finally heads out, Bottas complains his steering is pulling to the right, while Gasly reports he is "sliding in all corners".

Hamilton begins his first flying lap. He goes quickest in S1, going on to post a PB in the second sector. At the line, having gone quickest in S3 also, he posts 23.699 to go quickest by 0.040.

Leclerc subsequently improves to 23.848 to close to within 0.149s of Hamilton, while Raikkonen goes sixth with a 24.789.

Norris complains about "poor drivability".

Perez posts 25.034 to go 12th, just ahead of his Racing Point teammate. The car was pretty much designed before last year's buy-out, so the early part of this season is going to be a struggle for the newcomers.

Despite not being quickest in any of the sectors, only a PB in S1, Bottas goes quickest with a 23.684. However, Hamilton instantly responds with a 23.360, thereby going quicker by 0.32s... on 6 lap old tyres.

Replay shows Kubica clouting the wall as he entered the pitlane, appearing to cause some damage to the right-side of the car. Moments later, Raikkonen reports "damage to the pit wall"

Elsewhere, a slow Giovinazzi gets in the way of Norris and Russell.

Gasly improve to 12th with a 24.888, like his teammate the Frenchman is yet to try the soft tyres, preferring, as in testing, to do all their running on mediums.

A brave marshal runs along the pitlane picking up bits of debris, including a piece of floor from the Williams.

New team, new colours, but same old expletive laden radio call from Raikkonen.

On a new set of softs, Vettel heads out in a bid to improve. He goes quickest in S1, maintaining the pace into S2. At the line he posts 22.556 to go quickest by 0.804. That was despite a small mistake in the final corner.

No sooner has Magnussen gone second (23.334) than he is demoted by his Haas teammate who posts (23.112).

Leclerc and Hamilton are both set to improve, the Monegasque posts 22.749, while the Briton posts 22.292, to go quickest by 0.264. Both Ferrari drivers made mistakes on their laps, but 0.264s worth?

Hulkenberg can only manage 13th (24.870), around 0.4s off his teammate's pace.

With 9 minutes remaining, Verstappen heads out on softs, as Bottas can only manage 6th (23.422), the Finn running wide in a couple of corners.

Raikkonen looks set to improve, indeed, the Finn posts 24.402 to go ninth, having lost time in traffic in the final sector.

PBs in the first two sectors for Verstappen, who finally crosses the line at 23.481 to go seventh, 1.189s off the pace. As teammate Gasly posts 23.367 to go sixth, replay shows Verstappen having a lovely drift which no doubt cost him time.

Tenth and eleventh, the Renault pair are well-matched, Ricciardo having the slight advantage.

Albon is quickest through the speed-trap, ahead of Raikkonen, Kvyat, Sainz, Norris, Perez, Giovinazzi, Stroll, Hulkenberg and Ricciardo, which clearly has little relevance to outright lap times.

The session ends with no further improvements.

For a while it did indeed appear that Vettel, and Ferrari, might have that edge, but the fact is that the session ends with Hamilton 0.264s clear of his great rival, having topped the timesheets in all three practice sessions.

Behind these two, it's Leclerc, Grosjean, Magnussen, Gasly, Bottas, Kvyat, Verstappen and Ricciardo.

Hulkenberg is eleventh, ahead of Giovinazzi, Sainz, Perez, Albon, Stroll, Raikkonen, Norris, Russell and Kubica.

Coming up next, qualifying... when hopefully the BS finally ends.

Check out our Saturday gallery from Melbourne, here.