Paul Peterson held a narrow one-shot lead over defending champion Thomas Pieters as the D+D REAL Czech Masters moved towards a dramatic conclusion at Albatross Golf Resort.
The American, playing in just his 23rd European Tour event, had two top tens last season but missed his first three cuts of the 2016 campaign before finding some consistency in the spring and summer, and is searching for a first title.
Pieters claimed his maiden title at this event 12 months ago and is looking for a win here and next week at the Made in Denmark to potentially keep his Ryder Cup hopes alive.
Another man with his eyes on a place in Darren Clarke's Team is Matthew Fitzpatrick and he was just three shots off the lead at ten under, knowing a third-place finish would virtually assure his place at Hazeltine.
Swede Robert Karlsson was also at ten under, a shot clear of Ryan Evans, Graeme Storm, David Lipsky and Marc Warren.
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 to cut the gap to one shot and when he played a stunning approach on the fifth to within a foot, he was back at the top.
He then took advantage of the par five ninth for the third day in a row to move to 13 under at the turn.
England's Fitzpatrick birdied the first, fourth and ninth to sit ten under after ten holes, alongside Karlsson who turned in 32 but bogeyed the tenth after finding the water.
Scot Warren was four under on the day through 12 holes, with Evans and Lipsky both having picked up two shots and Storm one under for the day after a series of missed birdie chances.
David Howell and Jeff Winther were then both eight under around the turn.
