When the lights went out, polesitter Leclerc swung across Perez's bows to maintain the lead at La Source, where Carlos Sainz, starting fourth, locked up and then collided with Oscar Piastri running just behind from fifth on the grid on the inside.
The McLaren was pinched against the inside wall, damaging its suspension and ripping the side of the Ferrari's right-side sidepod, with Piastri slowing on the run downhill to Eau Rouge and later stopping on the first lap of 44.
