Daniel Vancsik will not be in the field this week to defend the title he won by seven shots last year, when he made 21 birdies and an eagle on the way to an 18-under 270.
It marked the Argentine's first-ever win on any of the world's major golf tours.
Welshman Bradley Dredge also claimed his first European Tour win at this event in 2003, keyed by a third-round 60 that was carded with a preferred lies rule in effect.
Dredge and countryman Stephen Dodd -- both in the field this week -- have a winning history in Portugal, having captured the 2005 World Cup for Wales at Vilamoura.
Next week on the European Tour is the Open de Andalucia, which was won by Lee Westwood last year.