A tenacious Marcel Siem turned one clear of a charging David Horsey midway through the third round of the Trophée Hassan II.
Three clear overnight, the 32 year old German Siem – needing a victory to give himself a chance of climbing into the Official World Golf Ranking’s top 50 on Sunday in the nick of time for a Masters Tournament invite – bogeyed the first and was caught by both 2011 winner Horsey and Finn Mikko Ilonen on the front nine.
However, he converted a ten foot birdie chance at the seventh and from 12 feet at the ninth to turn in 35 and lead by one on 13 under par.
England’s Horsey birdied the first but did well to salvage a bogey after a wayward drive two holes later.
The two-time European Tour winner completed his front nine in style, holing from 20 feet at the sixth then hitting his tee shot to five feet at the short eighth and striking his approach to the same distance at the next for consecutive birdies.
Ilonen, who picked up both his European Tour titles in 2007, had been part of a three-way tie on 11 under after lengthy birdie putts at the third and seventh, but missed the green at the eighth and bogeyed to drop into third.
Siem extended his lead with a two-putt birdie at the long tenth, but Ilonen joined Horsey in second when he became only the third player to eagle the hole today following a brilliant second to six feet.
Ilonen had a chance to narrow the gap at the top to one when he hit his approach to the 11th to within three feet, but missed out on a birdie when his ball moved a fraction as he addressed it.
That proved costly as Siem stuck his tee shot to within a foot of the 12th pin; the subsequent birdie taking him to 15 under and restoring his three shot lead.