Will Buller edged Formula Renault 3.5 championship leader Carlos Sainz Jr in the dying moments of free practice to top the times at Aragon on Friday.
The Arden driver was one of the last to take the chequered flag at the end of the session, deposing Sainz just seconds after the Spaniard had hit the front for the first time in the afternoon running.
Buller's team-mate Pierre Gasly also improved around the same time to slot into third place, as Roberto Merhi rounded out a top four that was covered by just eight hundredths of a second.
Merhi had only spent a little over a minute at the top of the times as the session ended with a flurry of improvements throughout the field.
Prior to the rush in the final few minutes, the afternoon running had been controlled by the Fortec duo of Oliver Rowland and Sergey Sirotkin, along with morning pacesetter Will Stevens and Jazeman Jaafar.
Stevens had enjoyed a relatively comfortable margin of 0.3 seconds over a closely bunched chasing pack in the morning, with Gasly, Buller, Rowland and Sainz all covered by a tenth of a second behind him.
Practice one: Pos Driver Team Time Gap Laps 1. Will Stevens Strakka 1m41.970s 19 2. Pierre Gasly Arden 1m42.284s +0.314s 20 3. Will Buller Arden 1m42.292s +0.322s 19 4. Oliver Rowland Fortec 1m42.311s +0.341s 19 5. Carlos Sainz Jr DAMS 1m42.425s +0.455s 20 6. Matias Laine Strakka 1m42.591s +0.621s 17 7. Marlon Stockinger Lotus 1m42.779s +0.809s 17 8. Jazeman Jaafar ISR 1m42.798s +0.828s 19 9. Matthieu Vaxiviere Lotus 1m42.851s +0.881s 20 10. Zoel Amberg AVF 1m42.925s +0.955s 17 11. Sergey Sirotkin Fortec 1m43.009s +1.039s 20 12. Marco Sorensen Tech 1 1m43.038s +1.068s 17 13. Norman Nato DAMS 1m43.040s +1.070s 16 14. Meindert van Buuren Pons 1m43.151s +1.181s 19 15. Roberto Merhi Zeta 1m43.218s +1.248s 18 16. Luca Ghiotto Draco 1m43.245s +1.275s 18 17. Roman Mavlanov Zeta 1m43.501s +1.531s 17 18. Nikolay Martsenko Comtec 1m43.686s +1.716s 13 19. Oliver Webb Pons 1m43.751s +1.781s 18 20. Beitske Visser AVF 1m44.329s +2.359s 18 21. Pietro Fantin Draco 1m47.004s +5.034s 6 Practice two: Pos Driver Team Time Gap Laps 1. Will Buller Arden 1m41.222s 18 2. Carlos Sainz Jr DAMS 1m41.257s +0.035s 21 3. Pierre Gasly Arden 1m41.280s +0.058s 19 4. Roberto Merhi Zeta 1m41.303s +0.081s 18 5. Nikolay Martsenko Comtec 1m41.531s +0.309s 20 6. Sergey Sirotkin Fortec 1m41.532s +0.310s 18 7. Marlon Stockinger Lotus 1m41.547s +0.325s 18 8. Jazeman Jaafar ISR 1m41.587s +0.365s 20 9. Will Stevens Strakka 1m41.605s +0.383s 17 10. Oliver Rowland Fortec 1m41.652s +0.430s 18 11. Norman Nato DAMS 1m41.671s +0.449s 19 12. Matthieu Vaxiviere Lotus 1m41.726s +0.504s 18 13. Zoel Amberg AVF 1m41.814s +0.592s 18 14. Luca Ghiotto Draco 1m41.816s +0.594s 18 15. Marco Sorensen Tech 1 1m41.825s +0.603s 19 16. Beitske Visser AVF 1m42.079s +0.857s 19 17. Pietro Fantin Draco 1m42.097s +0.875s 20 18. Oliver Webb Pons 1m42.140s +0.918s 19 19. Meindert van Buuren Pons 1m42.186s +0.964s 20 20. Roman Mavlanov Zeta 1m42.248s +1.026s 20 21. Matias Laine Strakka 1m42.249s +1.027s 17