John Joe Nevin booked his place in the quarter-finals of the men's Olympic bantamweight boxing with a convincing victory over Kanat Abutalipov of Kazakhstan this afternoon.

A supremely confident Nevin danced into the ring ready to take on an opponent who was a real step above Denmark's Dennis Ceylan, who the Irishman beat in the round of 32.

It was a cagey start to the opening round, with both fighters feeling each other out during the first minute, but the bout burst into life when Nevin landed two scoring counter punches. 

Nevin set his stall out to fight on the counter and enjoyed plenty of success leading with the left jab. He caught Abutalipov with a powerful right at the end of the opening round to lead 5-2.

Abutalipov continued to press forward as the second round got underway, playing into Nevin's hand and he picked his rival off beautifully and connected with a sweet uppercut that rocked the Kazak.

Abutalipov enjoyed his best spell of the match in the final minute of the round, catching Nevin with a quick flurry, but those gains were wiped out thanks to two powerful scoring body blows and the Irishman went into the final round leading 10-5.

Knowing that he was on the verge of an Olympic exit, Abutalipov came out with all guns blazing, but was unable to pin down the tricky Nevin.

The Mullingar fighter skipped around the ring, switching his footing at will and never giving Abutalipov a chance to settle as he threw punches from all angles.

A powerful left hook from Nevin rattled the Kazak fighter, who did rally in the closing minutes, but even though he managed to land with his jab he was still unable to win the round. 

A scoreline of 5-5 in the third was perhaps generous to Abutalipov, but it mattered little as Nevin eased to a convincing 15-10 victory.

Next up for the 23-year-old is the quater-final on Sunday evening against Oscar Valdez Fierro of Mexico.

Irish team captain Darren O'Neill will be the next Irish boxer in action. The Kilkenny southpaw is in against Germany's Stefan Haertel on Thursday afternoon and will be aiming to make it five wins in-a-row for Ireland at the Games.

The winner will meet either the Ukraine's Ievgen Khytrov, the current AIBA World middleweight champion, or Anthony Ogogo of Great Britain in the quarter-finals.

Meanwhile, Lennox Lewis was keen to highlight the shortcomings of the amateur game after watching Satoshi Shimizu's controversial bantamweight defeat to Magomed Abdulhamidov later in the day.

Lewis was ringside as Japan’s Shimizu, trailing 12-5 going into the final round, hurt the Azeri with a body shot and proceeded to send him to the floor five times in the round, during which time Abdulhamidov also received a two-point penalty.

Yet the judges still contrived to score the final round equal at 10-10, which, with the addition of two points to Shimizu's score, gave the Azeri, who had to be helped from the ring on unsteady legs, a 22-17 verdict.

That was greeted with deafening boos by the arena crowd, while Lewis said: "What I am concerned about is probably the judging. I would.. change the judging system. Get some judges who score all year round."

Angry Japanese officials marched to the competition office brandishing the $500 required to lodge an appeal.

Shimizu said: "I am so shocked about the result. I don't understand how I didn't win. I don't understand why the judges went against me. He fell down and the referee gave him almost 10 seconds to recover, which is not fair."

In a further controversy, Iranian heavyweight Ali Mazaheri was disqualified in the second round of his bout against Cuba's Jose Larduet Gomez after receiving three warnings for holding within a minute.

The incensed Iranian marched from the ring before the post-fight formalities and said: "I have never seen such a thing in the world. I could have won the bout but I had three warnings in a minute. I was not doing anything wrong."

In earlier bantamweight action, Californian teenager Joseph Diaz saw his Olympics come to an end with a 21-15 defeat to Cuba's Lazaro Alvarez Estrada in their second-round contest.

The sharp, all-action Diaz was a little unfortunate not to score more against the Cuban world champion, who tried to box coolly off the back foot but was often upset by Diaz's strong and accurate assaults.

Diaz was magnanimous in defeat, saying: "I had a really great fight with Lazaro who is an excellent fighter, and I gave everyone the show they wanted.

"I thought the scoring should have been a little closer but the judges didn't see that. But I'm not going to give Lazaro a downgrade. He's a good boxer and a great puncher and it just wasn't my day from the judges."