AGADIR, Morocco -- Marcel Siem remains on course to lift the Hassan II Trophy after increasing his lead to four shots at the end of the third round on Saturday.
Siem needs a victory at the Golf du Palais Royal to have any chance of breaking into the world's top 50 ahead of the Sunday night qualification cutoff for the Masters, and he will take a formidable advantage into the final day.
The German, who was three clear overnight, overcame a nervy start to card a 3-under-par 69 to move to 15 under overall and leave closest challengers David Horsey, Mikko Ilonen and Pablo Larrazabal trailing in his wake.
Siem bogeyed the first before steadying with five straight pars before the first birdie of his round at the seventh kept his lead intact.
His lead had been cut to a single stroke by this point, but back-to-back birdies at the ninth and 10th released some pressure and while he picked up another shot at the 16th, he gave it straight back with a bogey at the par-5 511-yard 17th.
"Until the 15th I was really happy with the round," Siem said. "I got over a tough start with tough condition and all the guys just behind me seemed to start really well and almost caught me up.
"I had to hole a few big putts just to stay ahead and then I managed to pull away a little bit," he explained. "But then 15 and 17 were disappointing because you are really looking to pick up a couple of shots there, but I managed to give one away.
"There was pressure there so it was great to make a few putts and pick up four in six holes," he added. "It is very nice to have the gap back for the start of the final round tomorrow. I am pretty confident at the moment so I know the swing is there when I trust it and just let it go. That will be very important tomorrow."
Siem's nearest challengers overnight Horsey and Ilonen both carded 2-under-par rounds of 70 despite threatening to cut the lead.
Englishman Horsey approached the turn in 33, but a disappointing back nine undermined his challenge. Ilonen, meanwhile, fired a 40-foot birdie at the third and followed it up by picking up another shot at the seventh.
The Finn then made an eagle at the par-five 10th, but three bogeys in his final six holes saw him settle on 11 under par overall, alongside Horsey and Larrazabal, who went round in 3 under par.
Austria's Bernd Wiesberger is in fifth on 9 under par overall, while England's Craig Lee is a stroke further back.