Colsaerts notched seven birdies in the opening 12 holes before eagling the 15th and 17th.
A booming tee shot and a short iron gave the 2012 Ryder Cup player a difficult but makeable putt at the last hole and his effort drifted agonisingly wide.
"When I made eagle on 15 I knew that if I birdied the last three holes that would have been a 59," Colsaerts told reporters.
"I parred 16 and then walking down the fairway on 17 I told my caddie after I hit a good drive, 'it's 59 or nothing'.
"I managed to make an eagle and then hit a good drive on the 18th. It's too bad it just shaved the edge," Colsaerts said of his putt.
"I thought it was going to be slightly left to right at the end and it kind of went straight and basically just left it hanging. It's going to be difficult to follow a score that low."
A round of 60 has been achieved 19 times on the European Tour, including twice in 2013 by American Peter Uihlein at the Dunhill Links Championship and Briton Scott Jamieson at the Portugal Masters.
Colsaerts' form deserted him after he played at the 2012 Ryder Cup in Chicago and he has slumped to 185th in the world rankings.
He was three strokes in front of Jamieson and Alexander Levy of France after the opening round in Portugal.
(Reporting by Tom Hayward, editing by Tony Jimenez)
Share
