Overnight leader Lucas Herbert opened up a two-shot lead at the halfway stage of the Irish Open, carding 67 in the second round on Friday to go 13 under at the Mount Juliet Estate in Thomastown.
Having carded an 8-under-par 64 on Thursday to set the clubhouse target, the Australian was three behind in the second round when he found the water on the third hole for a double bogey.
But he sank eight birdies in all to lead England's Andy Sullivan and Scotland's Grant Forrest who were tied for second.
"It was a little frustrating but I also felt like I did pretty well to scrap 67 out of that," Herbert said. "I holed some really nice putts and then missed some where I probably thought that was a good chance to make.
"The double [bogey] on three didn't help as well, so for a round that hopefully is not one of the better ones of the week. I felt like I did really well to get a lot out of it and put myself into a very good position going into the weekend."
Holder John Catlin was at 7 under overall while former world No. 1 Rory McIlroy was two shots further behind after carding a bogey-free 67, improving on his par score in the first round.
The four-time major winner got off to a steady start, making one birdie on the opening nine, before careering back to the clubhouse with four birdies.
"I got off to a better start and then once you do that you make a couple of birdies early, you start to feel like you can make a few more," McIlroy said.
"The greens were much better this morning than they were yesterday afternoon, as well. It felt a little easier to hole putts and that's really what I did. Everything was just a little bit better today and sort of added up to a better score."
England's Tommy Fleetwood and Ireland's Shane Lowry are also at 5 under through the first two days.
Richard Bland, who contended at the U.S. Open at Torrey Pines last month after securing his first career win at the British Masters, is in contention at 5-under entering Saturday.