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The judges scored the contest 15-15 after three rounds but Zou was given the verdict on countback

Belfast boxer Paddy Barnes will have to be content with a second Olympic bronze after suffering an agonising defeat by China's defending champion Zou Shiming in the light-flyweight semi-finals.

The judges scored the contest 15-15 after three rounds but Zou was given the verdict on countback.

Trailing 11-8 after two rounds, Barnes produced a huge effort in the third and appeared to have done enough to win.

Ireland's John Joe Nevin has qualified for the bantamweight final.

Mullingar man Nevin produced a classy performance to beat Cuba's world champion Lazaro Alvarez Estrada 19-14 in the bantamweight semi-finals to set up a gold medal contest with Britain's Luke Campbell.

Twice world bronze medalist Nevin won the first round 5-3 and he bossed the remaining two rounds to complete a 19-14 victory.

"I just believed I could beat the best in the world. The script was already written but I've re-written it," said Nevin after his win.

Barnes' contest was a far closer affair and the countback margin couldn't have been tighter with Zou edging it 45-44.

Irish team member Barnes, 25, was beaten 15-0 by the Chinese fighter at the same stage in the Beijing Olympics four years ago.

But the Belfast man was a different proposition four years on as befitting his status as the first Irish boxer to have won two Olympic medals.

"I gave it my all. I went in there and threw everything at him but he is so, so tricky," said a disappointed but gracious Barnes.

"And once I had him pinned down and was opening up, he's so smart and just picks you off and moves."

Barnes trailed 8-5 after the first round and the Belfast man felt that the opening three minutes ultimately cost him the fight.

"If I hadn't started so slowly, I would have won the fight."

Many observers felt Barnes' last-round rally might have been enough to edge the contest and the Irishman thought he had won the bout when it was announced that a countback verdict had been arrived at.

quote Last year, I had one fight in the World Championship and lost. I thought I was going nowhere Paddy Barnes

"I thought I had it because I threw more punches than him.

"Hopefully, he will be retired in four years time. I don't want to see that man again."

Before leaving the ring, Barnes had playfully pretended to strangle his Chinese foe and Zou responded by holding the Irishman's arm aloft.

"Last year, I had one fight in the World Championship and lost. I thought I was going nowhere," added Barnes.

"To go from that to lose to a three-time world champion and Olympic champion on countback. I'm happy."

Barnes and Conlan are among the five Northern Ireland medal winners at the London Games.

Katie Taylor won a women's lightweight boxing gold for Ireland on Thursday.