Sebastian Vettel laid down a further championship gauntlet to Lewis Hamilton by blitzing his title rival in final practice for the Monaco Grand Prix.
Vettel, six points clear of Hamilton in the championship standings, posted yet another record-breaking lap of the famous Monte Carlo circuit on Saturday morning to finish a third of a second clear of his Ferrari team-mate Kimi Raikkonen.
Indeed Hamilton, whose Mercedes team struggled during practice here on Thursday, was only fifth in the order, an eye-watering 0.835 seconds down on Vettel's best time. Valtteri Bottas finished third for Mercedes with Red Bull's Max Verstappen one spot ahead of Hamilton.
Jenson Button, back in the McLaren cockpit this weekend with Fernando Alonso set to tackle the Indianapolis 500, finished 12th, fractionally slower than his team-mate Stoffel Vandoorne.
But the 37-year-old Briton is poised to start last for his 306th and probable final grand prix, after serving a 15-place grid penalty following a series of changes to his Honda engine.
The narrow confines of the Monte Carlo street circuit makes it one of the toughest tracks on the calendar. Rookie Lance Stroll crashed out of practice on Thursday, and Esteban Ocon, the young Frenchman also making his Monaco debut, was in the wars here, too.
Ocon brushed the barrier on the entrance to the chicane at the swimming pool section, sustaining damage to his front-right suspension, before he headed straight into the wall.
His Force India mechanics will now face a race against time to get his car ready for qualifying later on Saturday.
There was also trouble for Red Bull's Daniel Ricciardo in the closing stages of the one-hour session as he suffered a brake failure.
British driver Jolyon Palmer meanwhile, was 18th, 2.7secs adrift of Vettel and nearly one second slower than his Renault team-mate Nico Hulkenberg.
