England's Matt Wallace remained on course to claim a first European Tour title despite seeing his lead cut heading into the final day of the Open de Portugal.
Wallace, who carded 10 birdies in a flawless opening 63 at Morgado Golf Resort, enjoyed a five-shot advantage at halfway after completing an error-free 66 when the delayed second round was completed on Saturday.
However, the 27-year-old Londoner could only manage a level-par 73 in round three to finish the day 17 under par, three shots ahead of Germany's Sebastian Heisele, who returned a 71.
England's Sam Walker sat four shots off the lead after a third round of 68, with France's Matthieu Pavon another stroke back on 12 under.
Gary Hurley was the only Irish golfer to make the cut after Ruaidhrí McGee, Kevin Phelan, Chris Selfridge and Michael Hoey all finished one side outside the cut mark.
Hurley carded three birdies in the last six holes to card a two-under 71 as he moved up the leaderboard to a share of 20th position on eight under.
Wallace, who won five tournaments in succession on the Alps Tour last year and six times in total, said: “It wasn’t very good today, I lost a bit of rhythm out there and just struggled really to get it round.
“I’d have liked to have been a couple better and that would have given me more of a cushion going into tomorrow. It is what it is and I’m going to prepare as well as I can for tomorrow.
“It could have been much worse. I battled really hard and made some good putts to save some pars. Hopefully I can put as much effort in tomorrow as I did today and play a bit better and hopefully I’ll be here tomorrow with the trophy.
“This week is the best I’ve probably played ever so I’m going to take that confidence into tomorrow. It is big but I try and dumb it down as much as possible — it’s just golf and I’m just going to go and give it my best.”
Heisele, who finished 28th on the Challenge Tour last season, hopes a fast start can apply some pressure to the leader.
“I didn’t play as well as I did for the first two days, so I’ll need something low tomorrow,” he said. “Matt is just going to keep doing his thing. I’ll try to get a few shots back tomorrow, early obviously to build some pressure, and take it from there.”