Branden Grace carded a third-round 72 and saw his five-shot overnight lead slashed to one ahead of the final day at the Alfred Dunhill Championship in South Africa.
After shooting 62 and 66 on Thursday and Friday, the 26-year-old local favourite looked to be closing in on a first European Tour title in over two years.
However, Grace's bid to end his drought suffered a setback after picking up five bogeys to leave him on 16-under par for the tournament, one shot clear of Lucas Bjerregaard.
The Dane himself brushed off bogeying the first and sank six birdies and an eagle at the 13th for a round of 66, which leaves him firmly in contention for a first Tour win.
England's Danny Willett sits two shots off the pace on 14 under, two clear of fellow countryman Andrew Johnston on 12 under.
Former major winner and another South African, Louis Oosthhuizen, sits on 10 under, six behind his compatriot.