Cormac Sharvin shares 54th spot, 14 behind leader Louis Oosthuizen, after firing a level-par 72 in the third round at the Perth International.
After squeezing into the weekend action in Australia after a nervy 75 on Friday, the Ardglass golfer was unable to mount a charge on Saturday.
The 23-year-old carded an eagle at the third, plus three birdies, but his round was hindered by five bogeys.
Sharvin is playing in his first European Tour event.
The county Down man, who helped Great Britain & Ireland win last year's Walker Cup, was given an invite to play in the European Tour event in Australia.
He produced an impressive seven-birdie 68 on Thursday but then found the going tougher on Friday.
Sharvin is likely to play most of his golf on the second-tier European Challenge Tour this season although he will hope to earn a number of invites to main tour events.
2010 Open champion Oosthuizen will take a three-shot lead into the final round in Perth after firing a 67 on Saturday.
American Peter Uihlein (71) and France's Romain Wattel (65) are sharing second place on 12 under.