Jean-Eric Vergne left it late to go to the top of the time sheets in the second practice session in Jakarta.
The Frenchman set a time of 1m 07.594s on his final lap to beat his DS Techeetah teammate, Antonio Felix da Costa by nearly four-tenths of a second on a hot and dusty track.
Jake Dennis, who had previously held the fastest time of the session, was third quickest for Andretti, just ahead of Mitch Evans and Edoardo Mortara.
Dan Ticktum and Oliver Turvey were sixth and seventh respectively for NIO, who halfway into the session, was briefly holding first and second.
Pascal Wehrlein was eighth fastest for Porsche, ahead of Antonio Giovinazzi in the Dragon Penske entry, with championship leader Stoffel Vandoorne rounding out the top ten for Mercedes.
Traffic proved once again to be an issue, as Envision Racing's Robin Frijns could attest to having lost one second in the final sector on his final lap, meaning he had to settle for 21st.