Valtteri Bottas topped the morning session of Day 3 of the Barcelona Tests with the fastest time seen so far whilst Vettel becomes the first to break down on track.
His time of 1.15.732s was only 3 tenths slower than his pole time last year and was set on the softest C5 tyre compound.
Esteban Ocon was second after a much needed productive morning for Renault. He ended up joint second with Carlos Sainz on the lap chart with 76 laps.
His teammate Ricciardo is subbing in for the afternoon session and is scheduled to do a race run which should give some good data on Renault’s situation.
Lance Stroll positioned the controversial Racing Point in another high position in third place with Kvyat’s AlphaTauri following him.
The Racing Point car looked to be keeping pace in sectors 1 and 2 with the Mercedes, as did the Renault, until Bottas put in a succession of very fast laps late in the session.
Red Bull had a difficult morning at first with Verstappen spending a lot of time off track after a kerbstrike but came out later on for a race run and ended up setting the most laps of the session with 86 laps.
Giovinazzi, Sainz and Grosjean all had uneventful mornings as their teams just got on with their programmes.
Vettel ground to a halt on the exit of turn 11 after losing power on the back straight.
Ferrari spent the rest of the morning changing the engine and Vettel did not go out with the power unit being sent back to Maranello for investigation.
Vettel had managed to set 40 laps by the time his morning ended but a lot of valuable time was lost especially considering it was the first red flag caused by a failure of the test.
Alfa Romeo’s yesterday was simply them running the system dry, not an actual car failure.
Nicholas Latifi’s Williams broke down on the main straight with a Mercedes PU issue just after Bottas set his absolute fastest lap.
PU issues for both Mercedes and Ferrari to investigate.
Testing continues this afternoon before Test 2 begins next Wednesday in Barcelona.