Seamus Power chipped in for an eagle two on the 14th hole en route to an excellent five-under 67 to remain firmly in contention at the AT&T Byron Nelson.
The Waterford native gained two shots on leader Sam Burns during the third round in Texas and will start the final round in a tie for seventh place on 16-under-par, just four off first place.
A steady start in a flawless round of golf, Power opened with eight pars before making a birdie on the ninth to turn on one under.
Power made another birdie on the 12th before holing out for the eagle on the risk and reward, short par-four 14th.
Three consecutive pars followed before Power took advantage of the par-five 18th to make birdie and sign for a five-under round, moving to 16-under going into Sunday.
Leader Burns shot a three-under 69 and now only holds a one-shot lead ahead of Korea's Kyoung-Hoon Lee who matched Power's 65.
After a 10-under 62 on Friday, the 24-year-old Burns had a mixed start after matching two birdies with a pair of bogeys in the first six holes.
Following two more birdies he almost eagled the par-five 18th but had to settle for tapping in for another birdie, which moved him to 20-under for the tournament.
An eagle on the par-five fifth boosted Alex Noren, who is chasing his first PGA Tour victory, but the Swede's day was tarnished by bogeys at the first and 13th as he shot a 70 to drop from second to equal-third.
Sharing that spot with Noren three strokes off the pace were South Africa's Charl Schwartzel and Americans Matt Kuchar and Jordan Spieth, who all shot 66.
Spieth repeated his impressive putting from the first day on the 18th, with the hometown hero again rolling in another eagle putt but this time doing it from the fringe behind the hole.
The final round will start earlier than scheduled due to inclement weather and Power will tee off at 8.39am local time (2.39pm Irish time), playing alongside American Doc Redman - who he is tied with - and Scott Stalling in the third-last grouping.