Paul Broadhurst, Guido Van der Valk, Adam Groom, Henrik Nystrom and Gonzalo Fernandez-Castano, are knotted in first after opening with rounds of 4-under-par 66.
Former European Ryder Cupper Pierre Fulke shot a 3-under 67 and is tied for sixth place with Raymond Russell and Markus Brier.
Broadhurst opened with a pair of birdies, then parred the next four holes. He collected his third birdie of the round at seven to make the turn at 3-under 32.
The 39-year-old Englishman dropped his first shot of the round at the 11th, but rebounded with a birdie at 12. Broadhurst bogeyed 16, but ran home a 25-foot birdie putt at the 17th. He reached the fringe in a two at the par-5 closing hole and two-putted for birdie and a share of the lead.
'Although I have been consistent recently, I was a little bit disappointed with Italy and the Forest of Arden because I got up there after a couple of days, but then fell away both times,' said Broadhurst, who won the Open de Portugal in April. 'We are just trying to get it a little more consistent but, with anything new, it feels a little bit odd.'
Van der Valk, the only Dutchman among the leaders, was only 1 under par through his first 11 holes. He recorded four birdies in a five-hole span from the 12th to take the lead at minus-5.
Van der Valk, who has been playing mostly on the Asian Tour this season, bogeyed the 18th hole to fall into the group at 4 under par.
'Of course, it is nice to play in front of your friends and family,' said Van der Valk. 'It is great. I live about 35 minutes north of here which means I can stay at home. It is great to stay at home for a week because we travel so much that it is great to sleep in your own bed for a week.'
Groom, a Challenge Tour member, had a much more up-and-down round than his co-leaders. The Australian completed his front nine at 1 under par, but his second nine featured only three pars.
Groom tallied three birdies, two bogeys and an eagle to grab his share of first.
'It was great today and I putted really well,' he said. 'I missed a short one at the last, but that was about my only mistake. If I hadn't putted so well I would have probably shot about level par. That was the reason.'
Fernandez-Castano, who along with Nystrom, teed off later than their co-leaders on Thursday, was 2 over after his front nine. He polished off his second nine in 29, including six birdies and one at the last.
'I played solid enough golf on the front nine, but I just made a few mistakes,' said Fernandez-Castano. 'But on this course you have to be really patient and see how it goes because if you are able to hit a few fairways in a row, you can make some birdies as I showed, but I was a little lucky too.'
Nystrom took sole possession of the lead with only three holes to play in the first round. He dropped back-to-back shots at 16 and 17 to fall to minus-3.
Nystrom birdied the last to get into the logjam in the lead.
Maarten Lafeber, the first local winner in 56 years when he titled in 2003, Joakim Backstrom, Robert-Jan Derksen, Marcus Fraser, James Heath, Fredrik Henge, Ben Mason, Damien McGrane, Mark Roe, Johan Skold, Kyron Sullivan and Benoit Teilleria are knotted in ninth at minus-2.
Defending champion David Lynn shot an even-par 70 and is tied for 36th place.