Paul Waring held a one-shot lead at the turn as the Nordea Masters got set for a thrilling conclusion at Hills Golf Club.
The Englishman started the day in a share for top spot with Thomas Aiken but two early birdies handed the South African the lead in the early stages.
Aiken would then bogey the fourth and fifth, dropping back to 12 under and sitting one behind Waring, who picked up a shot on the second.
Dane Thorbjørn Olesen was at nine under, a shot clear of Jazz Janewattananond, Maximilian Kieffer, Andrea Pavan, Haydn Porteous and Matthew Southgate.
Waring is playing his 200th European Tour event this week in his 11th season since coming through the Qualifying School, having missed large chunks of the 2011, 2012, 2015 and 2016 seasons with wrist and shoulder injuries.
He finished a career-best 60th on last season's Race to Dubai Rankings presented by Rolex, with a runners-up finish at the Joburg Open and a third at the Trophée Hassan II, but a tie for ninth in Morocco has been his only top ten this season.
Aiken hit a nice approach into the first to take the lead but Waring responded with a long putt on the second as his playing partner missed a birdie effort from six feet.
Another excellent approach into the third left Aiken with four feet for a birdie and he made no mistake to edge ahead.
He almost found the water on the next and failed to get up and down and when he missed the green off the tee on the par-three fifth, it was back-to-back bogeys.
Olesen got in trouble on the third to drop to eight under but an approach to five feet on the eighth helped get him back level for the day.
