In four races so far this season there have been three different winners from three teams.

Mercedes Formula 1 boss Toto Wolff said after a pulsating, wildly unpredictable Azerbaijan Grand Prix that he felt this was developing into an all-time classic season. On the evidence so far, it is hard to disagree.

In four races there have been three different winners from three teams. Each event has been fascinating in its own way. The past three have been thrillers. And in all of them there could have been at least one different winner had things worked out in another way.

The two big beasts in the two main teams are separated by only four points at the head of the championship. And while Lewis Hamilton and Sebastian Vettel are for now comfortably clear of the rest, it feels going into each race as if any one of the drivers from Mercedes, Ferrari and Red Bull could be potential winners.

Most critically, perhaps, the underlying pattern of the sport has changed, incrementally but fundamentally – for the first time since the start of 2014, the out-and-out fastest car on the grid is not silver, but red.

Barcelona is a track on which the teams conducted winter testing, in which Mercedes were quickets and the Ferraris struggled on the corners but it feels different now

If Hamilton has not been driving as well as he feels he could, so too are his team below the level they have been used to.

Vettel led the championship at this stage last season, and the Ferrari was proving the better and more flexible race car, but never was it the out-and-out fastest on average in qualifying. Now it is, if only by a few hundredths of a second. Vettel has been on pole for three of the four races.

All this is being reflected in individual race prices. Hamilton went off odds on for each race for over two seasons but for this race he is 6/4 joint favourite with Vettel. Variance is high too, three teams are closely matched and close racing has led to incidents, afety cars and varying strategy calls

At the prices, Vettel at 6/4 with William Hill here is attractive