Matthew Macklin claims he "switched off" in the later rounds after being stopped by world middleweight champion Sergio Martinez.
The 29-year-old Birmingham fighter, who descends from Irish parents, enjoyed some great backing on St Patrick's Day in his bid to claim Argentinian Martinez's belt at Madison Square Garden in New York on Saturday evening.
Macklin stood up well to Martinez throughout the bout and felt that he was in control for the most part by taking his 37-year-old opponent away from his game plan.
However, his hopes of success were dashed when he was knocked down on two occasions in the 11th round, causing his camp to withdraw their man from returning for the 12th.
Despite giving Martinez the toughest fight of his career, Macklin was disappointed that he could not maintain his momentum all the way to the end given that he was ahead on the judges' score cards at one point when the glove of Martinez touched the canvas in the seventh round.
Afterwards Macklin told Skysports: "Putting reckless pressure on would have been detrimental so I tried to feint, move my head, box, take him out of his rhythm, upset him a little bit and ease my way into the fight, then start putting the pressure on."
Asked what changed later in the fight, he added: "I switched off a little bit upstairs, stopped moving my head a little bit.
"It wasn't extreme fatigue because it wasn't that sort of fight but I certainly slowed a little bit, stopped moving my head, got a bit heavy on my feet and he caught me square a few times.
"That allowed him to get his confidence up and get into his rhythm."