Dino Zamparelli led an ART one-two-three in a rain-hit GP3 Series practice at Spa-Francorchamps, a session interrupted by a spectacular crash for rookie Konstantin Tereshchenko.
Briton Zamparelli hit the front early on with a time of 2m07.021s, which demoted erstwhile pacesetter Alex Lynn, before the championship leader was then pushed further down the order by Zamparelli's team-mates.
Marvin Kirchhofer was the second fastest ART man ahead of Alex Fontana with just 0.371 seconds covering the leading trio.
With light rain descending beginning to fall 15 minutes into the session - mostly within the first sector between Eau Rouge and Les Combes - further gains were not made by anyone in the field.
Lynn therefore maintained his fourth position, with Carlin team-mate Emil Bernstorff fifth and Matheo Tuscher just over a second off the ultimate pace set by Zamparelli.
While nobody made improvements during the final two-thirds of the session, it was not without its moments, with GP3 debutant Tereshchenko crashing in spectacular style.
The 20-year-old Russian went over the kerb at the final chicane after losing control under braking, sending his Trident car airborne, into a roll and then colliding with the barriers, before catching fire.
He was able to vacate the vehicle unharmed and returned to the pits under his own steam.
Once the session resumed after the red flag period, with less than seven minutes on the clock, the rain became heavier and it was not long before another incident occurred.
This time Marussia driver Ryan Cullen came a cropper, although in his case it was at the top of Eau Rouge.
He lost control of his car and made slight contact with the barrier, but it was enough to curtail the session with two minutes still left to run.
Pos Driver Team Time Gap 1. Dino Zamparelli ART 2m07.021s 2. Marvin Kirchhofer ART 2m07.372s +0.351s 3. Alex Fontana ART 2m07.392s +0.371s 4. Alex Lynn Carlin 2m07.437s +0.416s 5. Emil Bernstorff Carlin 2m07.696s +0.675s 6. Matheo Tuscher Jenzer 2m08.035s +1.014s 7. Nick Yelloly Status 2m08.232s +1.211s 8. Jimmy Eriksson Koiranen 2m08.271s +1.250s 9. Richie Stanaway Status 2m08.341s +1.320s 10. Patrick Kujala Marussia 2m08.374s +1.353s 11. Pal Varhaug Jenzer 2m08.495s +1.474s 12. Riccardo Agostini Hilmer 2m08.648s +1.627s 13. Luca Ghiotto Trident 2m08.674s +1.653s 14. Luis sa Silva Carlin 2m08.791s +1.770s 15. Santiago Urrutia Koiranen 2m08.826s +1.805s 16. Nelson Mason Hilmer 2m08.861s +1.840s 17. Jann Mardenborough Arden 2m08.918s +1.897s 18. Patric Niederhauser Arden 2m09.627s +2.606s 19. Ryan Cullen Marussia 2m09.843s +2.822s 20. Kevin Ceccon Jenzer 2m10.228s +3.207s 21. John Bryan-Meisner Trident 2m11.488s +4.467s 22. Konstantin Tereschenko Trident 2m12.027s +5.006s 23. Alfonso Celis Status 2m12.213s +5.192s 24. Robert Visoiu Arden 2m12.241s +5.220s 25. Sebastian Balthasar Hilmer 2m12.754s +5.733s 26. Carmen Jorda Koiranen 2m14.456s +7.435s 27. Dean Stoneman Marussia 2m18.487s +11.466s