Darren O'Neill has blamed a slow start for his 19-12 defeat to Germany's Stefan Hartel.

The Irishman said that he sparred with Hartel prior to the Games and believed that he had the measure of him, but did not implement his tactics quickly enough.

"I sparred him before the World Championships and thought I got the better of him there," said O'Neill.

"I thought I was able to out-box him. I sparred him before the qualifiers and he probably hit me a little there, but I knew what I was doing was wrong and I thought coming out that I had the capability of beating him.

"I was a little bit slow implementing the tactics in the first round, he got a lead and it was an uphill battle after that."

Hartel will now face Team GB's Anthony Ogogo in the last eight.