Thorbjorn Olesen picked up six shots in his first six holes to catch Robert Rock at the top of the BMW Italian Open presented by CartaSi leaderboard.
The 21 year old Challenge Tour graduate from Denmark exploded out of the blocks with consecutive birdies, sensationally holed his approach for an eagle at the next, then gained further strokes at the fifth and sixth to reach 16 under.
That was the same mark as overnight leader Rock, who was yet to tee off.
The 34 year old Englishman is looking for a first European Tour title and started the final round with a two shot lead, but with six players starting the day two behind and Olesen’s early charge there was all to play for at Royal Park I Roveri.
Olesen picked up another shot when he holed from a foot at the par five eighth for an outward 29 that gave him a one shot lead.
In-form Frenchman Grégory Bourdy two under through three – he chipped in at the third - as they reached 15 under to share third.
Francesco Molinari, playing in his home city of Turin and with huge galleries cheering him on, hit his approach to eight feet at the second for a birdie.
And he was even closer at the next, holing a four footer to join Rock and Bourdy in second.
Molinari’s challenge appeared all but over when he double bogeyed the seventh, but he holed a 20 footer for eagle at the eighth which was greeted by a huge roar from the crowd.
Rock had bogeyed the third after missing an eight foot putt, but he birdied the fifth and sixth then completed his hattrick with an eight footer at the seventh.
That left him second, one behind Olesen who was in the fairway rough coming down the last.
Bourdy was in third after birdieing from ten feet on the eighth, with six players – including Molinari – tied for fourth.