Derksen, who hasn't won on the European Tour since April 2005, had two early bogeys and eight birdies on the day.
Derksen opened his round with a birdie but dropped back with bogeys at Nos. 3 and 4. He had five birdies over a seven-hole span ending on the 12th hole and closed with birdies on two of the last three holes.
Rumford and Jacquelin were both bogey-free Thursday while Aphibarnrat had one bogey in his 4-under day.
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