Nico Rosberg admitted that only good fortune saved him from a massive crash in Belgian Grand Prix practice after his 190mph tyre failure.
The German had a frightening moment in the closing stages of second free practice when his right rear tyre failed on the flat-out run down to Blanchimont corner.
Speaking about the incident afterwards and how he had managed to stay out of the wall, Rosberg said: "Unfortunately it wasn't down to my skill. It was just luck that I stayed out of the wall."
Pirelli will conduct a thorough examination of the failed tyre to find out if the cause of the failure was debris or if it was actually structural.
Rosberg himself had no clue as to what happened.
"We don't know yet," he said. "It doesn't make sense to speculate about it; but it was quite a shock in the first moment because you don't expect it. Suddenly at 306km/h, or 190mph, to just lose control…."
With television images suggesting the tyre had started to fail on the run up to Les Combes earlier in the lap, Mercedes sources suspect that it could have been caused by damage from the exit kerb at Eau Rouge.
Mercedes executive director Paddy Lowe: "Different bits of video show some sort of unravelling up to a minute before the actual catastrophic failure. So the big question will be what's initiated that.
"I've never seen anything like that before, so we simply don't know.
"We'll have to wait and see. Pirelli will obviously take the tyre away and analyse it.
"We'll make some thorough checks to make sure that the car wasn't a contributor to it in some way."