Unbeaten American Stephen Fulton has been Carl Frampton's chief sparring partner in recent weeks, and admits he's the strongest fighter he's trained with.

Frampton's team brought the 12-0 Featherweight prospect in to help prepare him for Nonito Donaire, ahead of their mouth-watering showdown in Belfast on April 21st.

"My experience was great. He pushed me to the limit as well. I helped him with moving his head and not standing in a straight line," Fulton told the BoxNation Podcast.

"These last three weeks were a great experience for me because I haven't sparred with anyone with his resume and the high rate that he boxes at, ever. It also helped me with my career back home."

When asked about the strengths of Carl Frampton, Fulton stated that he had seen a significant improvement in the Northern Irishman's head movement.

"The power, the head movement. He's got great head movement now. He's got this movement where he comes in and it don't give you time to think. He's got an awesome stab to the body, and he can bring the right up top," explained the 23-year-old.

"He's the strongest person I've sparred so far. When I was young I sparred with Eric Hunter and a couple other pros, but he's got the power and is definitely the one that hit me the hardest since I been pro."

Steve Lillis asked the Philadelphia native what he thought would happen at the SSE Arena on Saturday night: "Donaire won't be able to maintain that movement so of course [Frampton]'s going to break you down physically and mentally, because he's not going to give you time to think. I know he has the mental toughness to take a punch and give a punch."

On episode 20 of the BoxNation Podcast, we preview Carl Frampton's Belfast barnstomer with Nonito Donaire and speak to Conrad Cummings, who also fights on the bill.

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