Seven players shared the lead after the opening day of the inaugural Belgian Knockout in Antwerp.

Testing conditions on a tricky course at the Rinkven International Golf Club prevented anyone breaking clear, with six further players just a shot off the lead.

European Tour rookies Gavin Green and Nico Geyger carded four-under-par 67s and sit alongside English duo Matthew Baldwin and Ryan Evans, Spaniard Jorge Campillo, Belgian Thomas Detry and Denmark's Jeff Winther at the top of the leaderboard.

Local favourite Nicolas Colsaerts, who shot a bogey-free 68, is in the group one shot back.

"Very happy. It's good to pull off a round like this, not a lot of mistakes, a couple of great saves. In control all day," Colsaerts said in his post-round interview.

"I knew that the scoring wasn't going to be that low. It's not an easy course, you can do a lot of mistakes.

"I had to make sure that I kept focused on what I needed to do on this tight and windy day."

Compatriot Thomas Pieters, the tournament host, faces a fight to make the weekend after a two-over 73.

In a new departure for the European Tour, the first two rounds of the event are over 36 holes of strokeplay with the top 64 progressing to a weekend knockout using a strokeplay format.

Three rounds of matches over nine holes will be played on Saturday, with eight players returning on Sunday for the remaining nine-hole knockout matches.