Formula One and its tyre supplier Pirelli face a full-on crisis after the British Grand Prix came close to being stopped for safety reasons due to a spate of explosive high-speed blowouts.
With television pictures broadcast around the world showing bucking cars scraping along on rear left wheel rims stripped of rubber, the drivers wrestling to keep them on the track, the sport breathed a sigh of relief that the race had ended safely.
Race director Charlie Whiting said he can't recall anything like four catastrophic failures in a race prior to this morning's race.
Lewis Hamilton was the first casualty when his rear tyre blew after eight laps at around 200kph, and he was followed by Ferrari's Felipe Massa, Toro Rosso's Jean-Eric Vergne, and McLaren's Sergio Perez.
Sauber's Esteban Gutierrez had a front tyre failure.
With the next race in Germany only a week away, Pirelli's motorsport director Paul Hembery said the Italian company is making the investigation a top priority.
McLaren team principal Martin Whitmarsh says the sport could not wait for a scheduled meeting of the governing FIA working committee later this week to discuss the situation.