Thomas Pieters saw his lead cut to one shot as he aimed for a successful defence of his title in the final round of the D+D REAL Czech Masters.
The 24 year old came into the final day at Albatross Golf Resort with a two-shot lead at 12 under but saw that cut to one after three holes by American Paul Peterson, with Matthew Fitzpatrick, David Howell and Robert Karlsson all at nine under.
A win for Pieters this week could also keep his Ryder Cup hopes alive ahead of the end of qualifying next week, with low scoring the order of the day after heavy rain overnight.
Peterson was quickly into a share of the lead after a two-shot swing on the first as he picked up a birdie with Pieters recording a blemish for just the fourth time this week.
Parity did not last long, however, as another swing on the second, this time with a Pieters birdie and a Peterson bogey, meant the Belgian once again found himself two shots ahead.
Peterson's topsy-turvy start continued with a birdie on the third and the gap was down to one shot.
England's Fitzpatrick is looking to help secure his place on the Ryder Cup Team this week and he birdied the first and fourth to sit alongside countryman Howell and Swede Karlsson, who were both also two under for the day in the early stages of their final rounds
South African Justin Walters was making a move as he turned in 32 to get to eight under alongside Dane Joachim B Hansen, who was also four under for his day after starting with five birdies but dropping a shot on the eighth.
Ryan Evans, Peter Hanson, Graeme Storm, Robert Rock and Jeff Winther were all also four shots off the lead.
Richard Bland recorded the 32nd hole-in-one of the European Tour season and the second of the week when he holed his tee-shot on the par three seventh.
The Englishman sank a five iron from 189 yards to join Daniel Gaunt in the history books, the Australian had aced the third on Thursday.
