Scott Redding produced a stunning late lap in Moto2 qualifying to take his first ever grand prix pole position.
Marc VDS Racing's Briton was the only rider to go below 2m11s with a last ditch flier to claim top spot by almost seven tenths of a second from Takaaki Nakagami's Italtrans Kalex.
Nakagami's 2m11.266s had looked good enough to earn him qualifying honours, while morning practice pacesetter Pol Espargaro's session never really got going.
The Spaniard, seeking to make it six Moto2 pole positions in a row, ended up seventh fastest on his Pons Kalex machine but never looked like troubling the front two rows throughout the session.
Redding, by contrast, was flying around the twists and turns of the Texan circuit. Yet he seemed on course to miss out on a front row start altogether as Nicolas Terol and Esteve Rabat improved late on.
But Redding's heroics in the dying seconds saw him pump in a 2m10.577s lap - demoting Terol to third and dumping Rabat onto the second row.
He will be joined on row two by Dominique Aegerter and Simone Corsi.
Injured frontrunner Thomas Luthi had to abandoned his earlier-than-expected comeback as he was still in too much pain during Friday practice.
Pos Rider Team/Bike Time Gap
1. Scott Redding Marc VDS Kalex 2m10.577s
2. Takaaki Nakagami Italtrans Kalex 2m11.266s + 0.689s
3. Nicolas Terol Aspar Suter 2m11.287s + 0.710s
4. Esteve Rabat Pons Kalex 2m11.383s + 0.806s
5. Dominique Aegerter Technomag Suter 2m11.606s + 1.029s
6. Simone Corsi Forward Speed Up 2m11.725s + 1.148s
7. Pol Espargaro Pons Kalex 2m11.838s + 1.261s
8. Xavier Simeon SAG Kalex 2m11.859s + 1.282s
9. Mika Kallio Marc VDS Kalex 2m11.925s + 1.348s
10. Julian Simon Italtrans Kalex 2m12.001s + 1.424s
11. Anthony West QMMF Speed Up 2m12.341s + 1.764s
12. Jordi Torres Aspar Suter 2m12.346s + 1.769s
13. Danny Kent Tech 3 2m12.399s + 1.822s
14. Marcel Schrotter SAG Kalex 2m12.529s + 1.952s
15. Randy Krummenacher Technomag Suter 2m12.579s + 2.002s
16. Toni Elias Avintia Kalex 2m12.714s + 2.137s
17. Johann Zarco Ioda Suter 2m12.757s + 2.180s
18. Mike di Meglio JiR Motobi 2m12.986s + 2.409s
19. Kyle Smith Avintia Kalex 2m13.014s + 2.437s
20. Sandro Cortese Intact Kalex 2m13.050s + 2.473s
21. Axel Pons Pons Kalex 2m13.094s + 2.517s
22. Ricard Cardus Forward Speed Up 2m13.121s + 2.544s
23. Ratthapark Wilairot Gresini Suter 2m13.229s + 2.652s
24. Mattia Pasini Forward Speed Up 2m13.295s + 2.718s
25. Alex de Angelis Forward Speed Up 2m13.382s + 2.805s
26. Yuki Takahashi Tady Moriwaki 2m13.863s + 3.286s
27. Louis Rossi Tech 3 2m14.108s + 3.531s
28. Alberto Moncayo Arginano Speed Up 2m14.649s + 4.072s
29. Doni Tata Pradita Gresini Suter 2m14.894s + 4.317s
30. Steven Odendaal Arginano Speed Up 2m15.321s + 4.744s
31. Rafid Topan Sucipto QMMF Speed Up 2m18.792s + 8.215s