The Citroen driver maintained a lead of 24.7 seconds over Jari-Matti Latvala's Ford through Sunday morning's first loop of three stages.
With the battle for the win settled, the podium fight looked set to provide final-day interest, but this contest has also now fizzled out.
A blistering start to the day from Ott Tanak suggested that M-Sport Ford's rising star would challenge Mikko Hirvonen's works Citroen for third place.
But a mistake on the morning's middle stage, Santa Marina, cost Tanak a lot of time and convinced him to call off the chase.
The spin also dropped Tanak behind Mads Ostberg to fifth place. Erstwhile leader Ostberg is 19.9s behind Hirvonen and reckons he has little chance of salvaging a podium place now.
Further back, debutant Hans Weijs lost his excellent sixth position when he rolled on the short La Sierra d'Almos stage.
Evgeny Novikov dropped down the order when he was given a 10-minute penalty for a tyre wear infringement overnight, but should still secure a points finish.
As was the case on Saturday afternoon, Rally 2 runner Dani Sordo has been blitzing the stages and setting a string of fastest times in his repaired Prodrive Mini.
In addition to entertaining his home crown and giving him a shot at rescuing a point, Sordo's burst of pace is well-timed as he and Ostberg top Citroen's list of contenders for its vacant 2013 works seat.