His bogeyless round included five birdies and an eagle at the par-5 eighth hole.
"I've been struggling a bit with my long game and (today's score) gave me a huge confidence boost," Hansen said on the European Tour Web site. "It was a fantastic way to come into this (tournament)."
Hansen holds a one-stroke lead over Sweden's Peter Hanson, the early frontrunner, South Africa's Thomas Aiken and India's Jyoti Randhawa.
A group of nine golfers shares fifth place at 5-under 67.
Sergio Garcia, the 2008 runnerup, shot 3-under 69 after bouncing back from an opening double bogey six.
Defending champion Ross Fisher of England opened with a 1-over 73 and is locked in a tie for 95th place.