In the first few seconds of the clip, we join two men in their car as they peer out the windscreen onto the road ahead of them.
There, we can see a silver-coloured car driving just in front of them... but something seems wrong from the off.
Unable to drive in a straight line, the car continually drifts between the two lines of the lane - even slowly meandering in front of oncoming traffic at one point.
"Slow down," we hear one of the men say. "I don't want us to get in an accident."
But, despite pulling back, and despite being aware of the danger ahead of them, the two men were unable to predict what would happen next.
Watch the shocking footage for yourself below:
Thankfully the two men seemed to be okay - and it is to their credit that they immediately rushed to check on the driver of the other car.
"Why did she just pull out in front of me?" we can hear the terrified woman ask them - and it seems as if, to that, there is no real answer.
While some have suggested the driver of the silver car was drunk, others have said that it is clear they were suffering from over-tiredness on the road.
Research by Think! has revealed that almost 20% of accidents on major roads are sleep-related.
They advise drivers to allow a 15 minute break between every two hours of driving - and to pull over to a safe place for a rest (not the hard shoulder) if they begin to feel tired whilst driving.
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