Julien Quesne bounced back from an early double bogey to card a 5-under 67 on Sunday and win the Italian Open by a stroke.
Quesne earned his second career victory on the European Tour at 12-under-par 276.
"After my double bogey, I just kept calm. I was thinking the winner would be 15 under and I was only five under. I thought 'Just keep working and we will see what happens'," said Quesne. "I am surprised to be here. The flags were very difficult all week so it was very difficult to make birdies and easy to make some bogeys."
David Higgins and Steve Webster shot matching 4-under 68s during their final rounds at Golf Club Torino to share second place at 11-under.
Fredrik Andersson Hed, who won this event in 2010, carded a 5-under 67 to move into a tie for fourth with Emiliano Grillo (68), Felipe Aguilar (71) and Nicolas Colsaerts (72) at 10-under.
Third-round leader Marcus Fraser held at least a share of the lead for the majority of the day, but bogeyed three of his last four holes to fall into a share of eighth place at 9-under 279.
Fraser entered the final round with a 1-stroke lead and birdied the first to maintain that advantage as Lagergren and Colsaerts, who were all playing together, also birdied the first.
Lagergren tripped to a double bogey at the third to fall behind, while Fraser bogeyed the same hole to drop to 11-under and into a tie for the lead with Colsaerts.
Colsaerts, though, bogeyed the fourth to drop a shot off the pace and hand the outright lead to Fraser.
At the sixth, Fraser dropped a shot as Colsaerts rolled in a birdie to claim the lead. But his lead did not last long as there was another 2-shot swing at the seventh, with Fraser converting a birdie and Colsaerts recording a bogey to put Fraser back on top.
Maximilian Kieffer and Higgins made it a three-way tie at 11-under with birdies at the 13th and 14th, respectively, before Kieffer bogeyed the 14th to lose his share.
He was replaced atop the leaderboard by Webster following his birdie at the 15th, but Webster and Higgins both bogeyed the 16th to fall to 10-under and leave Fraser alone at minus-11.
Fraser then birdied the 13th to move to 12-under and seemed well on his way to the win, but his collapse along with Quesne's late push paved the way for the Frenchman to collect the win.
Quesne had started the day four strokes behind Fraser, and quickly fell further behind with a double-bogey 6 at the second.
He would not drop another shot for the remainder of the day, however, and rallied back with birdies at the fourth and sixth to make the turn at 7-under.
After pouring in back-to-back gains at the 10th and 11th, Quesne followed three straight pars with a birdie at the 15th to move to 10-under and pull within two strokes of Fraser.
Quesne then chipped in from just off the green at the 17th before converting a 6-foot birdie putt at the last to meet Fraser atop the leaderboard and claim the clubhouse lead.
Fraser fell apart from there, tripping to a 3-putt bogey at the 15th to fall behind. He would follow that with another bogey at the 16th after an errant drive, and needing to birdie his final two holes to force a playoff, dropped another shot at the 17th to fall three shots off the pace.
NOTES: Quesne's other win came at the 2012 Open de Andalucia Costa del Sol ... The win was Quesne's seventh top-10 finish of 2013 ... Quesne is the second Frenchman to win the Italian Open since it became a part of the European Tour in 1972. The first was Gregory Havret in 2001 ... Quesne collected 250,000 euros with the victory and is expected to move inside the top 140 in the world rankings.