Cormac Sharvin carded a superb 65 at the third round of the Celtic Classic, to leave him five shots behind leader Connor Syme.
Sharvin finished the day with eight birdies. The only blemish in his round was a bogey on eight. He currently is in a tie for eight spot on ten under.
The other Irish left standing in the field at the Celtic Manor resort is Jonathan Caldwell. A round of 72 sees him on seven under.
A score of 63 has propelled Scotland's Connor Syme to the top of the leaderboard. He hit nine birdies in all and is one shot clear of overnight leader Sam Horsfield.
Sweden's Sebastian Soderberg is two shots off the lead on 13 under, with forner Ryder Cup player Pieters a further two strokes back in his first event for five months due to the coronavirus pandemic and the birth of his first child in July.
Pieters, who won a record four points on his Ryder Cup debut in 2016, held a three-shot lead after two eagles in the space of three holes around the turn, but ran up a triple-bogey on the 15th after topping his tee shot into heavy rough.
With the ball in an unplayable lie, Pieters was forced to go back to the tee on the short par four and pulled his third shot into a water hazard, eventually signing for a seven and then dropping another shot on the next.
Syme, who regained his European Tour card via the Challenge Tour last year, is seeking a first victory on the main circuit and has dropped just one shot - on the seventh hole on day one - so far this week.