Paul Waring saw his lead cut to a single shot after the third round of the Abu Dhabi HSBC Championship.
The Englishman started the day five clear but a one-over 73 left the door ajar for the chasing pack.
Waring's 18-under-par total is one clear of Niklas Norgaard, with Tommy Fleetwood, Shane Lowry, Thorbjørn Olesen and Sebastian Söderberg tied for third on 15 under.
Waring found a bunker with his opening tee shot and had to scramble par from eight feet, but looked to have settled down as he birdied the par-five second and hit his tee shot to eight feet at the short fourth.
However, he ran his birdie attempt five feet past and missed the return, before missing birdie putts at the next nine holes.
Finding sand off the tee at the 14th proved costly as he failed to save par from 15 feet.
Waring had produced the shot of his life with a fairway wood to inside four feet at the last on Friday, but 24 hours later ended up in a greenside bunker and had to settle for a 15th par of the day.
Waring joked after his round: “You've got to have an average day, haven't you?
“I'm a little bit disappointed – I felt like I could have put myself out of sight but four rounds of golf, you're always going to have a bit of an iffy run of holes, an iffy round of golf. If beginning of the week you had given me a one-shot lead going into tomorrow, I'd have snapped your hand off.
“I'm trying to remain positive that I'm still in the lead, looking forward to getting out there tomorrow.
“I wasn't at my best today, felt a little bit jittery in total honesty, I felt the greens were a foot-and-a-half quicker, they were breaking a bit more than what I was reading. I just struggled on them a little bit today.
“I was absolutely fine for the first few holes. Four I've hit a lovely tee-shot and three-putted and that just put me on the back foot a little bit. I didn't recover in total honesty. I went into a bit of a defensive mode – you're playing to win golf tournaments and you have to manage your emotions and what's going on around you.
“It's a game of golf tomorrow in the sunshine – I'm looking forward to the challenge of it now. I feel like my bad golf is out of the way now.”
Norgaard had four birdies against a single dropped shot in his 69 and admitted he is starting to feel like he belongs at big events following his first DP World Tour win at the Betfred British Masters hosted by Sir Nick Faldo.
“Feeling good because the game was not nearly as good as the first two days,” he said. “So I definitely had to be patient and made my first bogey all week on hole nine, which annoyed me quite a bit.
“But didn't try to force birdies or anything, just tried to do the same thing over and over again, and I'm very satisfied with today.
“Today playing in the final group I would have been so nervous if I had not tried that before. It's funny how it takes you, because a year ago, I really felt like a guest at these tournaments, and now I feel more at home.”
