Mercedes driver Lewis Hamilton topped an eventful first practice session in Monaco which came to an early end due to a loose drain cover.
Hamilton and team-mate Nico Rosberg traded times early on before the Briton moved clear with a time of 1:15.537 on the Ultra Soft tyres.
Rosberg was 0.101s behind in second place, though his incident caused the session to be halted four minutes earlier than scheduled.
A loose drain cover punctured Rosberg’s right rear tyre exiting Sainte Devote and the object bounced into the path of the pursuing Jenson Button, whose front wing sustained damage.
Both drivers were able to safely recover to the pit lane, though the session came to an early end.
Sebastian Vettel was 0.419s behind Hamilton to emerge as Mercedes’ closest challenger, with Red Bull fourth and fifth courtesy of Daniel Ricciardo and Max Verstappen.
Daniil Kvyat had an encouraging session for Toro Rosso by placing sixth, marginally behind Verstappen, with Force India drivers Nico Hülkenberg and Sergio Pérez seventh and eighth.
Kimi Räikkönen was ninth, Carlos Sainz Jr. 10th while Valtteri Bottas saved a lurid moment through the tunnel to place 11th.
Bottas’ Williams team-mate, Felipe Massa, was the first driver to encounter trouble as he slid wide and crashed at Sainte Devote, sustaining damage to the left hand side of the car.
Esteban Gutiérrez also saved a moment approaching the Nouvelle Chicane before an electrical issue halted his Haas at Portier.
Renault's Jolyon Palmer clipped the wall at Tabac and had to stop with damage to the right hand side of his car.