Scary failure for Buemi, more engine problems for Alonso

Sebastien Buemi had a major scare during Friday's opening practice session in Shanghai.

After a sudden and catastrophic double suspension failure on the Swiss' Toro Rosso under heavy braking, both front wheels sheared off the car and he was pitched into the barrier and gravel trap at high speed.

The incident brought out the red flags and caused dramatic scenes in the Faenza based team's pits, as Jaime Alguersuari's sister car was withdrawn from the session.

The early official word from the STR garage - where a shaken Buemi, 21, initially refused to discuss his crash as he stormed out - is that the team is not speculating about the cause until the damaged car is checked.

"At the moment, we do not know the cause of Buemi's accident, other than some element of the car failed. The driver is ok," said a spokesman.

Worryingly, one of the wheels had made its way into the spectator area, and while television replays seemed to indicate a camera had been struck, it is believed no one was hurt.

Another incident during the 90-minute session was an engine failure for Fernando Alonso, who retired in Malaysia two weeks ago with a blown 2.4 litre V8.

Ferrari said on Twitter that it "knew this engine wasn't too good", having been removed from Alonso's F10 after overheating in Bahrain.

The Spaniard had said on Thursday that he was not overly worried about his engine situation, with each driver limited to just eight V8s for the entire 19-race schedule.

"Right now, and we cross our fingers, we are maintaining the original plan," he is quoted as saying by El Mundo newspaper.