One clear of 2010 champion Marcus Fraser overnight, Wiesberger matched his own course record to reach 14 under par.
A 15 footer for birdie at the fourth and a five foot putt at the sixth kept him ahead on the front nine, and he forged clear with a spectacular inward 31.
The 26 year old Austrian barely missed a putt after the turn, holing a 12 footer for birdie at the tenth, converting from ten feet for another gain at the 12th, then preventing a first dropped shot in 36 holes by saving par from 15 feet at the 13th.
That was followed by a brilliant downhill 20 footer for birdie at the 14th, and Wiesberger displayed his all-round talents with a tee shot to two feet at the 16th and a chip to within a foot at last.
Australian Fraser played some fine golf in his 69, but in contrast to his playing partner struggled to get the putter going and now has five shots to make up in the final round.
Chile’s Felipe Aguilar (68) and England’s Oliver Fisher (67) share third on eight under, with Ryder Cup veterans Miguel Angel Jiménez and Paul McGinley a shot further back - but all will need something special to catch Wiesberger on Sunday.
| Pos |  | Player name | | Nat | | Hole | | Par | ||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 |  | WIESBERGER, Bernd | | AUT | | 18 | | -14 | ||
| 2 | | FRASER, Marcus | | AUS | | 18 | | -9 | ||
| T3 | | FISHER, Oliver | | ENG | | 18 | | -8 | ||
| T3 | | AGUILAR, Felipe | | CHI | | 18 | | -8 | ||
| T5 | | MCGINLEY, Paul | | IRL | | 18 | | -7 | ||
| T5 | | JIMÉNEZ, Miguel Angel | | ESP | | 18 | | -7 |
