Casares - Second-ranked Luke Donald overwhelmed Martin Kaymer 5 and 3 in the semi-finals of the World Match Play Championship on Sunday, setting up a showdown with fellow Englishman Ian Poulter in the final and another chance to take over as world No 1 for the first time.
Donald raced to 3 up after four holes and never looked back against the No 3-ranked Kaymer, clinching the match on the 15th with his seventh birdie of a mightily consistent round.
The 22nd-ranked Poulter - conquerer of top-ranked Lee Westwood in the last 16 on Saturday - won the other last-four match on the first play-off hole against Belgium's Nicolas Colsaerts, ranked 108th. Poulter was never ahead until Colsaerts missed a par putt on the 19th hole.
If Donald wins the final in Andalusia, he will supplant compatriot Westwood as No 1 and pick up a winner's cheque for 800 000 euros.
Donald, who extended his unbeaten streak in match-play singles to 12 matches, also beat Kaymer in the final of the Accenture Match Play in February.
He missed a great chance to leapfrog Westwood in the rankings last month, when he lost a play-off at The Heritage in South Carolina to Brandt Snedeker. But given his relentless form this week on the Finca Cortesin course in southern Spain and his durability in the one-on-one format, few would bet against him squandering a second opportunity.
Donald failed to make at least par on only one hole against Kaymer, salvaging halves with pressure putts on the 7th, 9th, 12th and 13th from between six to 10 feet to keep his foot pressed firmly against Kaymer's throat.
Poulter, who has been taken to the 18th in all five of his matches this week, was 3 down after seven holes but then never lost a hole as Colsaerts squandered chance after chance.
The flamboyant Englishman pulled back holes on the 8th, 15th and 16th - Colsaerts bogeying all three of them - before wrapping up his come-from-behind win at the first opportunity in the play-off.