Marcel Siem carded a 4-under 68 on Friday as he maintained the lead at the Trophee Hassan II.
Siem, who is seeking his third career victory on the European Tour and has a chance of earning an invitation to the Masters with a victory at this event, finished 36 holes at Golf du Palais Royal at 12-under-par 132.
"I am trying my best," Siem said about possibly making the Masters. "It is a tournament I have always wanted to play and if I can keep calm and play the way that I have been for the first two days here then I have a chance."
David Horsey bogeyed his final hole to finish his second round with a 5-under 67, dropping him into a tie with Mikko Ilonen (66) for second place at 9-under 135.
Pablo Larrazabal fired the low round of the day with an 8-under 64 to move into sole possession of fourth place at minus-8.
Siem started on the back nine and opened his round with back-to-back birdies at the 10th and 11th.
After parring the next three holes, he added a couple more birdies at the 15th and 17th before stumbling to a bogey at the 18th.
The German then opened his inward nine with three straight pars before dropping another shot with a bogey at the fourth.
He got those two strokes back with consecutive birdies at the fifth and sixth to move to 12-under, however, and traded a bogey at the seventh with a birdie at the last to end there.
"I think it should have been better than it was to be honest," Siem said about his round. "The bogeys on four and seven were a bit weird because I was in the middle of the fairway there. But otherwise, this course is always tricky and I should accept the 68 because it's always nice to go under par after such a low round the day before because that can be quite difficult to follow up on sometimes."
Horsey opened his round with four birdies over his first five holes before dropping two of those strokes with a double bogey at the par-3 eighth.
He got those back with back-to-back birdies at the 10th and 11th, and then added two more birdies at the 15th and 17th to move within two strokes of Siem.
But a bogey at the last dropped him into a tie with Ilonen, who traded a double bogey and a bogey with seven birdies and an eagle during his second round.
"I am pleased overall and in a good position going into the weekend," said Horsey. "I think you do feed off the positive vibes when you come back to a place where you have won and that is certainly the case for me this week. I am coming into form at the right time and I have been playing good the last few weeks."
NOTES: Horsey won this event in 2011 ... Ilonen is seeking his third European Tour win, but the first since the 2007 Scandinavian Masters ... Defending champion Michael Hoey carded a 3-under 69 on Friday to move into a tie for 24th place at 1-under-par 143 for the tournament ... The cut line fell at 3- over-par 147, with 66 players advancing to the weekend.