St Helens middleweight Martin Murray dealt WBC champion Sergio Martinez an almighty scare before ending up on the wrong side of a unanimous points decision in Buenos Aires.
All three ringside judges plumped for the home favourite by identical margins of 115-112 despite him being floored by his 30-year-old foe in round eight.
Martinez found himself on a canvas made greasy by incessant rain once more two rounds later but referee Massimo Barrovecchio ruled a slip, somewhat generously in light of the left-hook and glancing right-hand landed by Murray.
As in his world-title draw against Felix Sturm in December 2011, Murray (25 wins, one defeat, one draw) emerges with his reputation enhanced regardless of a first professional loss - domestic clashes with former Martinez victims Darren Barker and Matthew Macklin hopefully loom.
The quality of a truly great champion was in evidence over the final two rounds as Martinez (51-2-2) made sure of the win but he is unlikely to relish many more such gruelling examinations at 38 years of age.
Martinez, who was greeted by a spectacular fireworks display and a fervent crowd in excess of 40,000 inside the Estadio Jose Amalfitani, set an impressive tempo in the opener, attacking predominantly to the body as Murray operated behind a tight guard.
Murray landed crisp rights in each of the first two sessions, benefiting from Martinez's contrastingly languid stance, and a more solid shot found the target in three as the Argentinean appeared to become frustrated by his opponent's cautious style.
Razor-sharp assaults to the body and a slick upwards jab meant Martinez was doing enough to pick up the early rounds before a meaty low blow from Murray sparked a more eventful fourth, with both men trading successfully.
Having landed a pleasing right hook to the head towards the end of that stanza, the challenger scored to the mid-section in five and by the midway point Martinez found himself bleeding from the left eye as evidence of clean, straight punches coming his way and the tightening scorecards.
Further Murray rough-housing with the shoulder worsened the facial damage for Martinez, who responded with some eye-catching work to take round seven but the next three minutes belonged definitely to the Englishman.
Shortly after absorbing a stringing left-hook to the jaw, Murray landed yet another solid right and the backpedalling Martinez tumbled to the canvas.
A champion's response meant a bloodied nose for the challenger in nine, but there was controversy in the 10th as Martinez went down under punches in the neutral corner without receiving a count.
Nevertheless, it was a clear Murray round and made Martinez's recovery behind his educated jab in the face of relentless physical pressure a welcome relief for the increasingly anxious home crowd.
The upshot was a fight up for grabs and a stadium on its feet for the final three minutes, where Martinez operated skilfully on the other side of heavy weather and prevented Murray from securing the big finish he needed.