Friday practice began under glorious sunshine in the Azerbaijani capital for F1's second visit to the shores of the Caspian Sea.
Ocon learned the track quickly to post 1m 45.752s on supersofts for seventh in the intact Force India, as Massa took eighth with his 1m 45.968s on the softs.
It led to a chaotic conclusion as a number of drivers - including both Vettel and Hamilton - attempted to improve on their time.
With 40 minutes remaining in the session the supersoft tyres came out. Lewis Hamilton was looking fighty, but couldn't put a lap together on the congested street circuit. But even he had his moments, nosing towards a wall in Turn 2 soon after going fastest, and then ending his day crashing in to the wall in Turn 1.
Red Bull's Ricciardo ended his day in third place and was satisfied with the improvements that the team made across the day.
In the opening practice session, Bottas narrowly missed the barriers while Perez mangled both wheels on the right of his vehicle on Turn 8. Wheel tethers in F1 are meant to prevent such an occurrence, so you imagine that there will be an investigation as to how the tether on Perez's right rear failed. The duo did most of their running in the final few minutes.
Carlos Sainz was 13th ahead of Kevin Magnussen's Haas in 14th, the two Renaults in 15th and 16th and Stoffel Vandoorne's McLaren in 17th. When you can do consistent laps without any mistakes, you can get the tyres to work as well. Verstappen set a 1:44.410 on the super soft Pirellis.
Bottas, who had languished down the order after the run on softs, was the first driver to bolt on a set of super-softs half an hour in, but it was Raikkonen who disrupted Verstappen's dominance with his first proper effort on the compound.
"So yeah, they have found good set-up for now and we still have work to do on that". Hamilton himself then broke that with 1m 45.497s.
Kimi Raikkonen went fastest initially, quickly followed by Vettel who pipped the Finn to top spot. Azerbaijan, however, could be a turning point for the team that ended the day with both Verstappen and Daniel Ricciardo in the top three.
Two drivers - Sergio Perez and Jolyon Palmer - did their cars a power of no good.
Palmer hit the outside wall with his front-right corner midway through FP2, bringing the session to a halt. One more crash like that one could prove terminal to his career.
After a delay of about 10 minutes the session was restarted.
Yet it was a hard day for Vettel's title rival Lewis Hamilton who was over a second back in both sessions. It was only fitting that Alonso had to retire with an engine problem in practice as well. This really is getting ridiculous now, and if you ask me, enough is enough, and Honda need to go!
But Verstappen hit a barrier late on and while escaping unharmed, his auto suffered some damage.
"From lap one I felt really good in the auto, even though in the short runs in practice I could not take the maximum out of it because of traffic and yellow flags, so we can be quite happy with this".
What did you make of today's practice sessions? Should Mercedes be anxious after a lacklustre Friday? It's only practice so who knows, but it'll be fascinating finding out as the weekend progresses.