Aston Martin a close second, Mercedes third.
Porsche signalled their intent early on in the build-up to the 2015 Hankook 24 Hours of Dubai, by topping the timing the timing sheets at the end of the first free practice session of the event on Wednesday at Dubai Autodrome.
The Fachs Auto Tech Porsche 997 of Otto Klohs, Martin Ragginger, Jens Richter and Sven Muller setting the early pace, with a best lap time of 1:59.170 and with it suggesting that Porsche intend repeating the win scored last year by Stadler Motorsport Porsche.
Trailing the pace setters by a mere 0.118 was the KPM Racing Aston Martin in the hands of Paul White, Stefan Mucke and Jonny Adam.
Two times winners in Dubai, the Abu Dhabi by Black Falcon Mercedes of UAE driver Khalid Al Qubaisi, Jeroen Bleekemolen, Bernd Schneider and Andreas Simonsen were third quickest, 0.342 of asecond off the leading Porsche.
For teams the Wednesday free practice was optional and only 66 of the 95 entered teams took to the track. The session was used mainly to shakedown the cars and for drivers to get track time ahead of a busy schedule on Thursday with practice from 11:30 to 14:45.
This is followed by qualifying from 15:00 to 17:30 and then night practice between 18:00 and 20:00.
The race set to be flagged off by ATCUAE president Mohammed Ben Sulayem at 14:00 on Friday with the chequered flag waving to bring proceedings to an end at 14:00 on Saturday, followed by the podium ceremony.
Throughout the weekend Dubai Autodrome paddock will be a hive of activity with a myriad of off-track entertainment and attractions for the whole family, with free entry to the circuit - including access to grandstands and paddock area.
Wednesday Free Practice Top 5:
1. Fach Auto Tech 2 Porsche 997 GT3 R - 1:59.170
2. KPM Racing 1 Aston Martin Vantage GT3 - 1:59.288
3. Abu Dhabi Racing Black Falcon Mercedes SLS AMG GT3 - 1:59.512
4. Stadler Motorsport Porsche 997 GT3 R - 1:59.745
5. Ram Racing Mercedes SLS AMG GT3 - 2:00.196