Defending champion Thomas Pieters has a share of the lead at the end of day two of the Czech Masters after a late bogey denied Jeff Winther sole claim to top spot.
Winther produced a six-under round of 66 to go 10 under for the tournament, as overnight leader Ryan Evans faltered - one over for the day to sit five strokes off the overall lead.
A strong start saw Winther register birdies on four of his opening five holes having started on the back nine, while an eagle just after the turn put him in front.
A bogey at the par-four eighth cost Winther the outright lead, although he was delighted with his round.
"It was fantastic," he is quoted as saying by the European Tour's official website. "I was doing well for the first hole and I kept chugging away.
"The eagle at 10 [hole one] was a surprise because I was full sure I was in the bunker. There was one in there but it was Oli [Fisher], so I guess mine bounced around it and onto the fairway.
"I was a bit lucky, but I hit a great shot onto the green and a great putt too, so it was a thieving eagle."
Pieters, who just missed out on a medal at Rio 2016 and hit five birdies in a faultless round, added: "It's always nice to go bogey-free and make some nice putts. I'm hitting irons very well, my ball-striking has been very good the last few days. It feels controlled and stress-free golf.
"It's the same gameplan, I've actually been a little less aggressive this year, but it's paid off because my wedges have been a lot better than last year. Hit some three woods and if you can fly some bunkers out here, why not do it?
"All I can do is do my best this week and we'll see where it brings me."
The duo are four strokes clear of their nearest challengers - a group of six players tied on six under, including Matt Fitzpatrick, who occupies the final Ryder Cup qualifying spot.
Steven Brown, Tommy Fleetwood, David Howell, Peter Hanson and Robert Karlsson make up the rest of the chasing pack.