Justin Horo has revealed a breakdown in his relationship with former Parramatta coach Stephen Kearney is what delivered the powerful back-rower to Manly.

Despite establishing himself as one of the Eels' most reliable forwards in his first two seasons, Horo admits he fell out favour with Kearney at the start of 2012 - ultimately leading to his exit from the club.

The 26-year-old was dropped by Kearney, a New Zealand teammate of his father Mark during the 1990s, after playing in the first two rounds of 2012, and popped up for a game midway through the year while he also struggled with knee, ankle and shoulder injuries.

Following Kearney's sacking in July, Horo was recalled to the team for the final four rounds under interim coach Brad Arthur.

"I fell out of favour a bit with the coaches at the start of the year and I had a few injuries as well which didn't help when I was trying to work my way back into the team," Horo told AAP.

"It was nothing to do with outside the footy, it was just purely to do with on-field things. Steve wanted me to work on a few things.

"But I was always confident in my ability if I could string some games together.

"And I ended up getting called back into first grade and obviously it wasn't under Steve.

"That's the way it panned out."

The snubbing rocked the youngster's confidence, which took a further blow when he was told by Eels management he was welcome to look elsewhere for a start in 2012, despite having a year to run on his contract.

"I was a bit down on confidence and when it got to the end of the season I didn't know if I was going to get a crack again," Horo said.

But he couldn't be happier to have landed a one-year deal at Manly, where he says he has become well-acquainted with the Sea Eagles' renowned fitness guru Don Single.

Manly's gruelling pre-season schedule has convinced Horo that nothing will come easy under coach Geoff Toovey, but he says he is ready to prove himself worthy of a longer contract.

"I want to prove myself to Manly and I'd love to stay at the club," he said.

"I'm not really big on changing around too much.

"By no means do I think I've got a spot there in the back row given to me.

"I've come here with the expectation that I have to earn a spot. That's the way I'm looking at it."