Hansen, a Dane whose last win on the European Tour was at this event in 2007, birdied Nos. 3, 7 and 9, then eagled the par-5 No. 13 to pull within one shot of Wood at minus-5. He pulled into a tie with the 21-year-old Englishman with a birdie at No. 15, then sank a 22-foot putt on No. 17 for a birdie that gave him the lead.
Hansen missed a 20-foot birdie putt on the 18th.
Wood birdied the third and sixth holes, as well as the 11th, 12th, 13th and 15th.
Former British Open champion Paul Lawrie was at 4-under 68 and was joined in seventh place by Simon Dyson and Francesco Molinari. Nick Dougherty and Soren Kjeldsen headline a group of 10 players tied at minus-3.