Hahn had eight birdies and an eagle at the par-5 third hole and zoomed past Ricardo Santos for a two-stroke lead halfway through the tournament. Hahn committed a bogey on the first hole he played Thursday but hasn't had a bogey since in moving to 16-under 126 for the tournament.
Santos, the first-round leader, shot 66 Friday and is at 14-under after 36 holes. Oliver Fisher, who closed with four straight birdies for an 8-under 63 Friday, is in third at 13-under and David Horsey, 64 in the second round, sits in fourth at 12-under.
Play was halted for about 90 minutes in the morning due to heavy rains and some players were unable to complete the second round because of darkness. The suspension came halfway through Santos's round but he still completed the day without a bogey.
Hahn started his second round at the ninth hole with a birdie and, with a birdie at No. 14, he was 2-under through nine holes.
He posed three straight birdies at 18 and then at Nos. 1 and 2 before the eagle at the 504-yard third hole. A birdie at the fourth hole made his 6-under in a five-hole span. Birdies at Nos. 6 and 8 allowed him to pass Santos for the lead.