He got saved even after roughly damaging his front wing, when his car hit the drain cover at the exit of Ste. Devote, at the end of the session.
It appeared that Nico Rosberg had already pulled the cover up while running over it, which resulted in the puncture of the left rear wheel of his Mercedes.
It was not confirmed during the incident what Button had hit, until the photos of the broken cover emerged.
F1 race director, Charlie Whiting also reached the scene, soon after the session.