The three-time podium finisher surpassed his previous best time to edge out nearest rivals Vergne (Andretti) and Prost (e.dams-Renault).

Vergne, who suffered a heavy crash in FP2, went quickest early on coming within four tenths of the Brazilian’s best time. But di Grassi responded midway through the session to take the top spot where he remained unchallenged.

Nelson Piquet Jr (China Racing) finished fourth in front of Scott Speed (Andretti) and Antonio Felix da Costa (Amlin Aguri), who despite a lock-up at T5, looks like a contender for today’s qualifying session which gets underway at 12:00 (local time).

Stephane Sarrazin (Venturi), Sam Bird (Virgin) and the Dragon pairing of Jerome D’Ambrosio and Loic Duval rounded out the top-10.