Lewis Hamilton set another track record to pip team-mate Valtteri Bottas to the fastest time in Practice Three as Mercedes continued to set the pace at the Spanish GP.
Hamilton, seeking to secure back-to-back victories in Barcelona, posted a 1:17.281 on supersoft tyres to outpace Bottas by just 0.013 seconds.
But Ferrari were very close behind the two Silver Arrows on the same tyres, with Vettel two tenths down on Hamilton’s benchmark and Kimi Raikkonen three hundredths of a second off his team-mate.
The session was brought to a premature end when Brendon Hartley had a big crash at Turn Nine in the final minutes, the Kiwi putting a wheel in the dirt and being sent flying into the barriers, completely destroying the rear of his Toro Rosso.
Red Bull kept their cards close to their chest with Daniel Ricciardo and Max Verstappen doing much of their running on the medium tyres in their heavily revised RB14.
Ricciardo put in a late effort on the supersoft tyres but was only fifth, seven tenths down on Hamilton, while Verstappen was down in 12th.
Verstappen’s session was curtailed by an electrical problem on his power unit, with his engineers facing a race against time to fix the issue for qualifying, which gets underway at 2pm on Sky Sports F1.
The Dutchman is also under investigation from the stewards after failing to stay to the left of a bollard before rejoining the track after going wide at Turn One.
Kevin Magnussen took the ‘best of the rest’ tag for with sixth for Haas, ahead of team-mate Romain Grosjean, with Carlos Sainz eighth in the leading Renault.
Fernando Alonso ensured the updated MCL33 finished in the top 10 once again as he took ninth, with Pierre Gasly just behind for Toro Rosso.
But Williams had another session to forget as Lance Stroll and Sergey Sirotkin were the two slowest cars once again, Stroll also running into the gravel for a second time this weekend.
Will Lewis Hamilton and Mercedes make it back-to-back victories at the Circuit de Catalunya? Watch the Spanish GP exclusively live on Sky Sports F1 from May 11-13. Get Sky Sports F1.