It means Barrier and La Marra head into the final round at Magny-Cours with the former leading by three points. Race winner Staring, meanwhile, is also mathematically in with a shout, albeit 22 points adrift with only 25 remaining.
Behind Barrier, Guarnoni completed the podium, ahead of Savadori and La Marra, while Christoffer Bergman completed one of his better results of the season with a run to sixth.
Fabio Massei took the sole Honda in the field to seventh place, ahead of Leandro Mercado, Markus Reiterberger and Ondrej Jezek.
Nurburgring podium winner Kev Coghlan, meanwhile, retired with technical problems.