Lewis Hamilton and Max Verstappen crashed out of the Italian Grand Prix – with the halo appearing to save Britain's seven-time world champion from serious injury.
After Hamilton left the pit-lane on lap 26, Verstappen drew alongside his championship rival at the Variante del Rettifilo in Monza.
Hamilton moved to his left to defend his position at the right-hander, with the Mercedes driver narrowly ahead for the ensuing left-hander.
Verstappen ran out of room, and ran over the kerb which launched his Red Bull out of control and into Hamilton's Mercedes.
The rear of the Dutchman's airborne machine ran over the top of Hamilton's helmet, with the protective halo device absorbing the impact. The front of Verstappen's Red Bull was then beached in
the gravel, and resting on Hamilton's car.
A furious Verstappen said: "That is what happens when you don't leave any room." The Dutchman jumped out of the cockpit and stormed away, without checking on Hamilton's condition.
One lap later, Hamilton eventually emerged from his car, appearing to be unharmed in the second collision in five races between the championship protagonists.
Mercedes swiftly reassured fans with a Twitter post which read: "For everyone asking, Lewis is OK. He's on his way back to the paddock now."
The incident was referred to the stewards to investigate after the race.