Rory McIlroy will have to overturn a three-shot deficit if he is to get 2017 off to a winning start at the BMW SA Open.
The world number two overcame a back problem to fire a 67 in round three at Glendower Golf Club but that was not enough to close the gap on England's Graeme Storm, who also shot a 67 to get to 17 under.
A win for Storm would represent a remarkable comeback for a player who lost his European Tour card by just 100 euros 83 days ago but was handed a reprieve when United States Ryder Cup star Patrick Reed failed to play enough events.
England's Jordan L Smith has won the EuroPro Golf Tour and the Challenge Tour in the last two seasons and is enjoying his debut campaign on the European Tour, sitting at 13 under alongside South African Jbe Kruger.
McIlroy twice caught Storm on Saturday, firstly when birdies on the second and eighth sandwiched a stunning eagle from 157 yards on the par-four seventh and again when he made a hat-trick of gains from the 11th.
A bogey on the last stalled McIlroy's progress but Storm was a picture of consistency, making birdies on the four par-fives and the seventh as he extended his bogey-free run to 41 holes.
"I am just really pleased that I kept the momentum from yesterday and played really nicely and holed some good putts," Storm told the European Tour's Official website.
"I find myself now in a position that I have only been in a couple of times over the past few years. Things have been difficult and last year was a tough year but it has given me a new lease of life and I hope to continue playing well.
"I thought I had lost my card and all of the privileges that come from playing on the European Tour and when that happens you realise that you can't afford to lose it."
McIlroy added: "I'd like to be a few shots better or at least a few shots closer to the lead. Hopefully I can get off to a good start tomorrow and put a bit of pressure on Graeme and it will be interesting."