Hahn, an American who finished No. 120 on the European Tour this year, made 12 birdies on the shorter Tour Course at the PGA Catalunya Resort. The European Tour said it would not count as a record because of preferred lies in the soggy conditions.
Hahn started on the back nine and opened with five straight birdies. He put together four straight birdies around the turn and closed with a tap-in birdie for 58.
Hahn moved from a tie for 114th into the top 15 with two rounds remaining. The top 25 and ties earn a European Tour card for next year.