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