Lucas Bjerregaard continued his recent excellent form to move into a share of the lead as the Omega European Masters edged towards a dramatic conclusion at Crans-sur-Sierre Golf Club.
Defending champion Matthew Fitzpatrick had entered the day with a two-shot lead but he turned in level par to leave the door ajar, with Bjerregarrd and Mike Lorenzo-Vera the men to take advantage.
The Dane was five under for his first 11 holes to get to 15 under alongside Frenchman Lorenzo-Vera, who turned in 32.
England's Fitzpatrick was then at 14 under, two shots clear of countryman Daniel Brooks.
Bjerregaard arrived in Switzerland off the back of two top tens as he looks for a second European Tour title, while Lorenzo-Vera is searching for his first win in his 167th appearance.
Should Fitzpatrick win, he would be the first man to successfully defend the title since the late, great Seve Ballesteros in 1978 and in the process become the youngest Englishman to get to five European Tour wins.
Bjerregaard made the first move from the chasing pack as he hit a huge drive down the first but still needed to hole a 35-footer to get within three of the lead.
Lorenzo-Vera also birdied the first but he did not need a long putt, hitting a stunning approach to tap-in range to get within one of Fitzpatrick.
Both men in the final group then needed smart up-and-downs to save par on the second but Fitzpatrick could not repeat the trick from the trees on the third and the lead was shared.
A smart pitch on the fifth from Bjerregarrd then brought his second birdie of the day and when he hit a lovely approach into the next, there was a three-way tie at the top.
Lorenzo-Vera made a bogey on the fourth to drop out of that group and Bjerregaard led alone when he drove the green at the par four seventh and got down in two.
Lorenzo-Vera got back within one as he left his drive just short of the fifth and got up and down, playing a remarkable flop-shot on the next to help save his par.
Fitzpatrick then three-putted from the fringe on the sixth and after starting the day two ahead, he was two off the lead.
Lorenzo-Vera followed Bjerregarrd's lead on the seventh to share the lead and Fitzpatrick got a boost on the same hole as he got up down from a bunker for a birdie.
The lead was not shared for long, however, as Bjerregaard took advantage of the par five ninth after finding sand to turn in 30 and edge ahead.
Fitzpatrick then birdied the same hole after laying up, while Lorenzo-Vera also made a birdie after a remarkable sand save.
Brooks turned in 33 to sit three of the lead, one ahead of American Doug Ghim and Japan's Hideto Tanihara.
China's Wu Ashun was then at ten under, a shot ahead of clubhouse leaders Darren Fichardt and Phachara Khongwatmai.
Frenchman Adrien Saddier made the 32nd hole-in-one of the season and second of the week when he holed a seven iron from 192 yards on the 13th.
