Australian surfer Phil MacDonald eliminated titleholder and reigning world champion Andy Irons from the lucrative Billabong Pro Mundaka.

MacDonald, who secured his best result to date last week with a runner-up finish to Irons in France, gained revenge on the Hawaiian when he and American wildcard Nathan Yeomans sent the world champion crashing out in the first round of the $US250,000 ($A362,500) event.

"Conditions were pretty hard out there and I don't think it was really fair," MacDonald said of the deteriorating surf in Spain's Basque region.

"You'd take off without really knowing what the wave what was going to do.

"The wildcard (Yeomans) got an eight (out of 10 score) and put us on alert, but I was lucky to get a couple which ran a bit further.

"Just one of those days."

Irons' elimination opened up the race for the 2004 world title.

His two main rivals, six-time world champion Kelly Slater and West Australian Taj Burrow, both progressed to round two.

Slater advanced with a win over WA's Jake Paterson and Burrow scraped through behind Hawaii's Kalani Robb in the tricky conditions.

Irons, who claimed his fourth WCT of the year in France last week, wasn't overly optimistic about his title chances.

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