Ferrari's Charles Leclerc had just led away easily from pole ahead of McLaren driver Oscar Piastri, while behind Carlos Sainz first attacked Piastri at Ste Devote and then slid off at Casino Square with a suspected puncture.
Perez was eliminated by Kevin Magnussen trying to poke his nose into a gap on the run up the hill before Massenet, with their crash wreckage then swinging across the track and taking out Nico Hulkenberg as he tried to come by from just behind.
