Derksen, who shot a 66 in the first round, mixed six birdies with a double bogey and a bogey on the 7,361-yard Pinx Golf Club course for a total of 9-under 135. Thailands Thongchai Jaidee and Kang Wook-soon of South Korea were tied for second.
It was a difficult day, Derksen said. Every par was actually a good hole, and I managed to even squeeze in a few birdies.
Jaidee had three birdies and two bogeys to finish with a 71, while Kangs 69 featured four birdies and a bogey.
Im very happy with that, Jaidee said. Early the wind is not very strong I think. But the last seven holes (had) very, very strong wind, and very difficult to play the course.
Overnight joint leader Mark Brown was three strokes off the pace after following his first-round 65 with a 73. The New Zealander was joined by Martin Pablo of Spain (69) and Italys Alessandro Tadini (71).
Gonzalo Fernandez-Castano of Spain, who shot an eagle and six birdies Friday to share the first-round lead, slumped to a 74 and sits at 4 under along with five other players.
Three-time major winner Ernie Els and Henrik Stenson of Sweden both shot 74 and are 2 under.
After clear skies and light breezes Thursday, Els said Fridays playing conditions came as something of a shock.
It feels like were back in Scotland today, said the South African, who shot five bogeys against three birdies. Its windy, cold. A good test of golf. I had a tough time out there today.
Els said the greens on the course were tough enough without the added challenge of the weather.
Its difficult to read the greens and Ive been having my problems there, he said. I left about four or five shots out there on the greens.
Former Masters champion Fred Couples struggled with five bogeys and a double bogey for a 76 to join a group of 21 players at 1 over, including Irelands Paul McGinley.
Defending champion Graeme McDowell of Ireland missed the cut after following Thursdays disappointing 76 with a 73 to sit at 5-over 149.
Obviously not what I had in mind for my title defense this week, McDowell said. I played a little better today, but I really didnt have it on the greens the past two days.
The tournament is jointly sanctioned by the European, Asian and Korean PGA Tours.