Tyrrell Hatton fired a brilliant birdie at the last to win the Italian Open and secure back-to-back European Tour titles.
Last week's Alfred Dunhill Links Championship winner carded six birdies - including five on the back nine - in a flawless 65 on Sunday to win his first Rolex Series event.
It had looked like the tournament would be decided by a play-off, with clubhouse leaders Ross Fisher and Kiradech Aphibarnrat alongside Hatton on 20 under par as he stood at the 18th tee.
But the 26 year old coolly rolled in his birdie putt from around 15 feet at the last to get to 21 under and clinch the trophy.
Fisher, who was also pipped to the post by Hatton in Scotland last week, and Aphibarnrat had to settle for a share of second place, while overnight leader Matt Wallace finished alone in fourth on 19 under courtesy of a brilliant chip-in birdie at the 17th.
It's amazing to win one but to win back-to-back and defend in two weeks is unbelievable - Tyrrell Hatton
Hatton began the day in a tie for second, two shots behind Wallace, but found himself four shots off the lead at the turn after making just one birdie on the front nine.
The Englishman, who celebrated his birthday on Saturday, caught fire on the back nine, reeling off four straight birdies from the 12th to catapult himself into contention.
After making pars at the 16th and 17th, Hatton knew he would have to do something special at the last to avoid a play-off.
And he obliged, holing his tricky putt in front of huge crowds at the 18th to win his third European Tour title.
Hatton said: "It's amazing to win one but to win back-to-back and defend in two weeks is unbelievable.
"I knew I needed a low score today, and the front nine was pretty slow and I didn't really get any momentum.
"I was fighting myself, trying to stay patient and J.B, my caddie, was saying 'good things will come'.
"Although I found it hard to believe, I tried to stay patient. In the end, I guess I got my reward.
"The end goal is to get as high as possible up the world rankings. Obviously the last two weeks have helped a lot.
"To win a Rolex Series event is very special. They are new for this season and all of the players look forward to playing in them.
"I'm just happy that I could win one of them after a poor showing in them during the summer."
After setting the course record at St Andrews with an 11-under-par 61 in the final round of last week's event, Fisher enjoyed another successful Sunday at Golf Club Milano.
The five-time European Tour winner started the day five shots behind Wallace but closed the gap courtesy of five birdies on his front nine.
He began his back nine with another gain at the tenth before picking up a shot at the short 12th to grab a share of the lead.
Fisher missed a birdie chance at the 13th but did not let that affect him, knocking in from six feet at the next to get to 20 under.
The 36 year old was overtaken at the top by Aphibarnrat after he made birdies at the 11th, 12th and 14th to get to 21 under, but after Fisher had safely parred his final four holes to sign for a 63, a double bogey at the 16th dropped Aphibarnrat into a tie for second.
The pair faced an anxious wait as Hatton - in the final group alongside Wallace - played his last few holes but were left disappointed as he made a birdie at the 18th.
Aphibarnrat made a stunning start on Sunday, opening his round with four straight birdies to get to 18 under.
The 28 year old dropped his first shot of the day at the eighth after leaving his par putt just short but recovered with a birdie at the ninth. And he made back-to-back birdies at the 11th and 12th to take a share of the lead on 20 under.
He holed his close-range birdie putt at the long 14th to take the outright lead but carded a disappointing double bogey at the 16th to fall back to 19 under.
A birdie at the next from six feet took him back to 20 under and he safely parred the 18th to finish in a tie for second.