It's the first time in Season 9 that one of the Maserati cars has topped a session, despite the team looking strong during pre-season testing. Mortara's teammate, Maximilian Guenther, finished the session in seventh place for good measure.
Fresh from a disappointing result in Hyderabad last time out, Jaguar TCS Racing's Sam Bird was on a mission and finished the Friday practice in second, 0.158s off Mortara's time. Sacha Fenestraz of Nissan also had a good FP1, slotting into third on the timesheets. Both Nissan cars managed to get in the top 10, an achievement also seen by Jaguar, NIO 333 and Maserati.
Just minutes into FP1, Envision Racing's Sebastian Buemi brought out the red flags after a heavy impact with the walls of this rapid street circuit between Turn 9 and 10. The incident destroyed the right side of his car, with the Envision team likely in for a long night ahead to get it repaired for tomorrow's action.
READ MORE: Full FP2 classification
The Season 2 Formula E champion and top average qualifier so far this season was very apologetic on the team radio and is fresh from the disappointment of losing out on a podium place in Hyderabad after a post-race penalty for "overpower usage".
Once the session resumed, with another ten minutes added for the delay to running, most of the grid set out to get as much experience on this 2.921km track as possible. However, the green flag conditions didn't last long as home hero ABT CUPRA's Kelvin van der Linde came to a halt.
The 26-year-old South African reported a driveshaft issue and stopped on the corner of Turn 7. Not going anywhere, FP1 was once again red-flagged to rescue his ABT CUPRA before the session once again got going with five minutes left on the clock.
Mahindra Racing's Lucas di Grassi ended his session early as he reported problems with his GEN3 machine. Parking at the chicane, di Grassi said he'd had a "suspension and rear-end failure" and that the "car was bouncing on the ground, but I managed to save it."
Avalanche Andretti's Jake Dennis' FP1 was also impacted by problems, with the driver sitting second in the Drivers' World Championship not getting many laps in. The team that uses TAG Heuer Porsche powertrains have been very competitive so far this season, with Dennis winning the first race in Mexico City and finishing second in both races at the Diriyah doubleheader.
Free Practice 2 gets underway at 09:10 local time tomorrow, with qualifying following at 11:40 and the Cape Town E-Prix Round 5 at 16:00.