Filippi lapped the Marina Bay circuit in 1:59.444s to defeat Carlin's Max Chilton by 0.052 seconds.
Following the earlier free practice session held in wet conditions, a dry track meant even more pressure was on teams to guesstimate their set-ups for the final qualifying session of the season.
Further complicating matters were the two tyre choices on offer, soft and super soft, with iSport's Jolyon Palmer appearing to have pulled off a masterstroke by topping the times using the harder of the tyre options with half of the session gone.
But in the final reckoning the super soft-shod cars of Filippi and Chilton outpaced him by over half a second, and Palmer was also eclipsed by the similarly soft-shod Esteban Gutierrez of Lotus.
Fabio Leimer was fifth for Racing Engineering, ahead of points leader Davide Valsecchi of DAMS. Valsecchi's title rival, Luiz Razia, was only ninth fastest for Arden, despite monstering his car around to the best of his ability, so he remains 25 points adrift at the season finale.
The session was red flagged with 1m25s on the clock when Nigel Melker stuffed his Ocean-run car into the barrier right beneath the marina grandstand. That meant those who had planned late flying laps were thwarted, and the session was not restarted.
Expected frontrunners such as Felipe Nasr, Giedo van der Garde and James Calado found themselves stranded down in 13th, 14th and 15th respectively.