Sweden's Anton Karlsson fired an eight-under-par 63 to claim the lead after the first round of the Belgian Knockout in Antwerp.
Karlsson carded an eagle, seven birdies and a single bogey at Rinkven International Golf Club to enjoy a two-shot lead over Chris Paisley, Dean Burmester and Gonzalo Fernandez-Castano.
Gavin Moynihan carded a one-under par round of 70 and is tied for 40th, one shot better than compatriot Michael Hoey.
The top 32 from each side of the draw after 36 holes of traditional stroke play will advance to the knockout stages over the weekend.
Players will then go head-to-head over nine holes of stroke play, with the player with the lowest score advancing to the next round until there is just one left standing.
Karlsson is seeking a first European Tour title after graduating from the qualifying school for a second time last year, the world number 317 being part of a nine-way tie for second behind Justin Harding in Qatar in March.
Scotland's Robert MacIntyre, who has finished runner-up in each of his last two starts, is part of a six-way tie for fifth on five under par following an opening 66.
Belgium's Thomas Detry gave the home fans plenty to cheer with an opening 67, although tournament host and his World Cup-winning partner Thomas Pieters was 143rd in the 144-man field after a 77.
