McLaren’s Jenson Button set the fastest time and Ferrari experienced another worrying engine failure in Friday’s opening practice session for the Formula One Chinese Grand Prix.

Button’s time of 1 minute, 36.677 seconds at the Shanghai circuit put him seven-hundredths of a second ahead of Mercedes’ Nico Rosberg. Their respective teammates Lewis Hamilton and Michael Schumacher were third and fourth on the timesheets.

The session was red flagged late after a frightening crash involving Toro Rosso’s Sebastien Buemi. Both front wheels flew off simultaneously under braking at the end of the main straight in what appeared to be a suspension failure.

The Swiss driver was unhurt in the accident, which could have been far more serious if not for generous run—off room, but was gesticulating angrily to his mechanics after returning to the garage.

Red Bull’s Sebastian Vettel was fifth fastest in practice and his teammate Mark Webber was eighth, separated by the Renault pair of Robert Kubica and Vitaly Petrov.

Fernando Alonso was forced to park in a billow of smoke and flames after yet another Ferrari engine failed. The team has been going through engines at an alarming rate early this season, and unless a remedy is found, the problem will hurt the team’s championship challenge because grid penalties are invoked once eight engines have been used.

Alonso’s teammate Felipe Massa was 10th in opening practice, behind Force India’s Adrian Sutil. The Italian team confirmed Friday that it was experimenting with some, but not all, of the components of an F—duct -- an aerodynamic mechanism that had been used to good effect this season by McLaren, which pioneered the technology.

More In: Motorsport | Sport