FINAL ROUND LEADERBOARD: (GB & Ire unless stated)
-19 A Quiros (Spa) -16 P Lawrie -15 R Karlsson (Swe), R Fisher, Steve Webster
Selected: -13 S Hansen (Den) -12 R McIlroy -9 L Westwood -7 D Clarke -5 M Angel Jimenez (Spa)
Quiros took the lead early on Sunday and never looked back
Alvaro Quiros shot a final round of 68 to win the Portugal Masters by three shots, but Order of Merit leader Robert Karlsson slipped down the leaderboard.
The Spaniard finished on 19 under to beat Paul Lawrie (67) by three and Karlsson (71), Steve Webster (68) and Ross Fisher (71) by four.
Quiros, overnight leader with Karlsson and Fisher, took the lead when the third round finished on Sunday morning.
And the 25-year-old went from strength to strength to seal an impressive win.
Karlsson went into the final day seeking his third title in a row and to strengthen his lead at the top of the European Order of Merit with two events left.
But he fell two shots behind Quiros when the Spaniard fired in a 50-foot birdie putt on the first green of his final round.
The Swede responded with three birdies in a row to regain a share of the lead but he dropped a shot at the 8th and never got back into contention for the title.
Quiros took full advantage to surge three shots clear of the Ryder Cup star but Fisher found a rich vein of form and joined the Spaniard at 17 under after a seven-foot birdie putt on the 12th.
But the tournament's fate was effectively sealed when Fisher dropped back with a run of three successive bogeys while Karlsson found water at the 17th.
I didn't play that great today and hit a few indifferent shots
Quiros, who had a difficult 2007 after badly injuring his wrist following victory on his European Tour debut event in the Alfred Dunhill Championship, holed out for the win with a five-foot birdie putt at the last.
"I hit the ball very well for the first three rounds but my putting was amazing in the last round, my best club today," he said.
"It's great to win again after all the trouble of last year. My main target coming here this week was to try to qualify for the Volvo Masters and now I've done much better than that."
Quiros dedicated his victory to golf legend Seve Ballesteros who is fighting for his life after surgery to remove a brain tumour.
"My caddy told me that Seve always wanted to beat everybody and today I drew inspiration from thinking about the way he played his golf," he added.
Karlsson now leads Padraig Harrington by around £246,000 in the money list, with both players skipping this week's Castello Masters in Spain to concentrate on the season-ending Volvo Masters in two weeks' time.
Although the two players are likely to slug it out in Valderrama for the European Order of Merit title, Lee Westwood, Miguel Angel Jimenez and Henrik Stenson are also in the hunt.
"I didn't play that great today and hit a few indifferent shots," said Karlsson. "It was a poorish swing on 17 and that cost me badly.
"But up to then I played well and I've got a bit closer to winning the Order of Merit. There'll be a lot to play for now at Valderrama."
The lowest score of the final day belonged to Bristol's Chris Wood, who won the Silver Medal for best amateur in this year's Open.
Wood turned professional after his heroics at Royal Birkdale and his final-round 65 saw him finish in the top-10 for the first time in the paid ranks.
He is now scheduled to attend the second stage of Q School at Jerez in Spain, working towards earning a Tour card for 2009, despite his finish in Portugal earning him a place in the Castellon Masters.
The Volvo Masters takes place from 30 October to 2 November in Spain.