The 20 year old Englishman shot to fame with his opening 65 at Sandwich, which was the lowest ever round by an amateur in The Open Championship and gave him a share of the lead.He was then part of the victorious Great Britain & Ireland Walker Cup side before joining the professional ranks, producing a top-ten finish in his first event in Austria.
Lewis’ seven under par round at Oceânico Victoria Golf Course saw him cut through the field, and at 21 under for the week he finished two ahead of Rafael Cabrera-Bello.He started with birdies from five feet at the first and fifth, but the real fireworks were saved for the back nine.
Tiger Woods needed five tournaments to land his first professional title, while Rory McIlroy did not taste success until his 38th European Tour event.
"I've not thought about the money - I was thinking about winning," said the new champion, who had an incredible 22 birdies and only one bogey in the last 52 holes.
“I've got a long way to go. I'm nowhere near the player I want to be, so I'll put this win behind me at the end of the year and start fresh next year.”
Lewis was only in seventh spot with seven holes to go before his late birdie blitz, and with previous joint leaders Peter Hanson, Christian Nilsson, Felipe Aguilar and Cabrera-Bello all finding water entering the closing stretch, he was suddenly three clear.
He kept his nerve to par the dangerous final hole and had to wait the best part of an hour before a victory that changes his life was confirmed.
Instead of facing a trip to the European Tour Qualifying School in December - he entered the week 234th on The Race to Dubai and 621st in the Official World Golf Ranking - he is exempt for two seasons and a rich young man already.
"I would not have expected this at all," he added. "I was really dreading going to the Qualifying School at the end of the year, but it looks like I've skipped that."
Instead he will be making a World Golf Championships debut in China next month and leaps to third place on The Ryder Cup points table, as well as entering the all-important top 60 of The Race to Dubai.
Lewis, shocked to have won so early in his career, has his feet on the ground, however, and stated: "I'm a long way behind Rory and have a long way to go.
"To have two years on The European Tour, I would not have dreamt that at the beginning of the week, so I'm really pleased."
Amazingly, Lewis was five strokes outside the halfway cut mark when he bogeyed the opening two holes of his second round on Friday.
But he turned that into a 64, was four behind Cabrera-Bello with 18 holes to go and seized his chance brilliantly as those ahead of him made mistakes.
"I was just happy shooting in the sixties no matter where I finished. If you had said I would finish 21 under I would have said 'No way',” he added.
Cabrera-Bello hooked into the lake off the 12th tee and ran up a double bogey seven, dropped another stroke two holes later, but hit back to grab solo second with a hat-trick of birdies from the 15th.
Just missing his eagle attempt on the long 17th, though, meant he had to hole his approach to the 463 yard last to force a play-off, and when he failed to do that Lewis knew he had won.
Joint third with Nilsson and Aguilar were England's David Lynn, France's Gregory Havret - both had best-of-the-day 64s - and South African George Coetzee.
Afterwards Lewis reserved special praise for his caddie Colin Byrne.
“To have his experience is excellent,” he added. “I don't think I thanked him in the speech at the prize giving, and I'm just really gutted now that you've just reminded me.
“I'll make it up to him next week and try to get another win. But Colin is just a great guy, really down to earth, and I thank him for everything.”