A dominant Mercedes made it three out of three in Barcelona practice, with Lewis Hamilton's new track record fractionally quicker than team mate Valtteri Bottas. Ferrari’s running was better than Friday but they couldn’t match their rivals, while a huge late crash for Toro Rosso’s Brendon Hartley brought an early end to the session.
Hamilton was just 0.013secs ahead of Bottas, with Ferrari’s Sebastian Vettel a quarter of a second behind the pacesetter and team mate Kimi Raikkonen a further three-tenths back in fourth. Red Bull opted to run on the slower medium tyres and saw Daniel Ricciardo finish P5, ahead of the improving Haas pair of Kevin Magnussen and Romain Grosjean.
Renault’s Carlos Sainz was able to squeeze into P8 just ahead of McLaren’s Fernando Alonso, while Pierre Gasly’s late effort for Toro Rosso saw him complete the top ten.
The windy conditions proved tricky for the drivers on Friday, but the early signs in this third and final session were positive, with Hartley – the first to register a time – and Nico Hulkenberg both reporting better track grip.
Most teams began the session on supersoft tyres, but Mercedes decided to send their drivers out on the soft compound – and it paid off. Bottas – the FP1 pacesetter – and Hamilton tussled for top spot throughout the first half hour, the latter winning the initial battle.
It was another impressive early showing from the Silver Arrows, who had previously only had a car in the top two in FP3 once this year. But their championship rivals Ferrari and Red Bull – shod with medium tyres – were up there, too.
And with just over 20 minutes of the session remaining, Vettel dealt Ferrari’s hand with a superb lap on the supersoft rubber. He went two-tenths quicker than Hamilton to temporarily move into P1, but the Briton immediately regained top spot after switching to the supersofts.
While the top teams battled, Williams' Lance Stroll made a trip through the gravel and Ricciardo went for a spin at Turn 13 on the mediums. Not much changed in the final stages of the session, with the Silver Arrows - and Hamilton in particular - enjoying an impressive start to Saturday.
Away from the top three, Haas continued to show signs of improvement - but McLaren and Renault will certainly prove a challenge in qualifying with their top-ten finishes.
Force India took a while to get going but weren’t far off the top ten – Esteban Ocon was two-tenths behind Gasly – while Sauber had to settle for P15 and P18. It was, however, another miserable session for Williams, who saw Sergey Sirotkin rock bottom again and Stroll in P19.
The unluckiest man was Hartley, though. In the closing minutes the New Zealander got a wheel on the grass entering Turn 9, spun and hit the barriers hard, ripping the rear off his Toro Rosso. He walked away to be taken to the medical centre for precautionary checks, where he was quickly given the all-clear, but engineers will surely struggle to rebuild his car in time for qualifying.
So what did we learn? Mercedes look very good this weekend and arguably have the momentum heading into the qualifying session. But you can’t write off Ferrari or Red Bull…