Reigning Moto2 champion Acosta, who will ride a GasGas Tech3 KTM in his debut season in MotoGP, posted the quickest time of the three days of running on the final session on Saturday.
The Spaniard's 1m58.189s was 0.066s faster than KTM test rider Pol Espargaro and over two tenths quicker than Johann Zarco on the top Honda bike.
MotoGP's shakedown was usually reserved for test and rookie riders, but this year's concession rules have allowed Honda and Yamaha to use their race riders, meaning Zarco was joined on track by fellow racers Fabio Quartararo (Yamaha), Joan Mir (Honda), Alex Rins (Yamaha), Luca Marini (Honda) and Takaaki Nakagami (Honda).
Acosta, using KTM's carbon chassis on the two bikes he rode during the day, suffered a number of minor accidents on his way to the fastest time, which was seven tenths slower than last year's pole position time, set by world champion Francesco Bagnaia.
Acosta's time, however, was quicker than the fastest lap time in the Sepang race.
Source: Autosport