Dutchman De Vries had appeared to be coasting to victory when he opened up a commanding three stroke lead over the field, reaching the 15th hole four under par for his round, but the Dutchman bogeyed both the 16th and 17th holes to fall a stroke behind Olesen, who led in the clubhouse after a superb seven under par 64.
Olesen, who is also 20 years old, came into the tournament in fine form after finishing tied 13th in the Iberdrola Open Cala Millor Mallorca on The European Tour last week
Scotland’s former Ryder Cup player Andrew Coltart and Englishman Lloyd Kennedy finished in a tie for third, three shots off the pace on seven under par after rounds of 68 and 67 respectively.
Colm Moriarty of Team Ireland signed for a one over par round of 72 and a share of 50th place on a 3 over total with an aggregate of 287. A double bogey on the 6th the biggest setback on the opening nine holes which he completed in 38 shots. But three birdes on 10, 11 and 12 set him back on track with the only dropped shot on the 17th.