George Coetzee won his second Tshwane Open title by two shots after an impressive back-nine birdie run on his home course.
The South African, who is a member at Pretoria Country Club, entered the final round with a two-shot lead but found himself two shots back after posting back-to-back bogeys on the 3rd and 4th holes.
He then delivered a putting masterclass, needing just ten strokes on the greens to birdie five of his next eight holes from the eighth and open up a three-shot advantage before play was suspended due to thunder and lightning at 3.37pm.
The final four groups returned to the course an hour and 34 minutes later and, despite a further 17-minute delay, Coetzee held his nerve to card a 67, stay at 18 under and finish two shots ahead of England's Sam Horsfield.
Playing partner Horsfield finished with three birdies in a 67 to edge a shot ahead of Korhonen, with Chilean Felipe Aguilar, Frenchman Sébastien Gros and South African Daniel van Tonder then at 14 under. Scotland's Scott Jamieson finished in 7th a shot further back.
Coetzee has overcome a lot since he last lifted the trophy in 2015, and said the home crowds were a big factor in winning his fourth European Tour title.
"A lot has happened since the last time I held that trophy," he said. "I broke my ankle and I kind of needed to show myself that I could win on Tour again and it's nice to come and do it again in front of the home crowd.
"They were amazing, I don't think I could have done it without everybody out here supporting me the whole week.
"On the eighth hole I started making everything, me and the greens became one. That really made it easier for me to not worry so much about where I'm hitting it."