James Tedesco's first season as a Sydney Rooster couldn't have gone any better.

Not only did Tedesco win a premiership in his first year at the club following six seasons at the Wests Tigers, he was also a key member of Brad Fittler's successful NSW Origin side and has been selected as Billy Slater's successor for the Kangaroos fullback spot for the upcoming Tests against New Zealand and Tonga.

"It was a hard decision to leave the Tigers but I want to come to the Roosters because I wanted to win a premiership," Tedesco told NRL.com.

"The Roosters have been a successful club for a number of years and just the attention to detail that Robbo (coach Trent Robinson) puts in at training and for myself personally is something that's been different for me.

"To do all that I've done in my first year at the club has really exciting and I'm really proud of myself and the team for what we've been able to do this year.

"Of course it was the right (move), but in saying that the Tigers will always hold a special place for me as that's where I played my junior footy and where I made my debut."

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Tedesco's switch of clubs meant he left the team with the third-worst defensive record in the league to the best defensive side in the competition in 2018, and the fullback said the Roosters left their best to last - holding the Storm to just one intercept try in the grand final.

"Our defence has been our main focus and our backbone this season," Tedesco said.

"We knew at the start of the year that that would win us a premiership.

"Defensively it was our best game all season - you could feel an increase in energy out there and we gave them no opportunities.

"There's no doubt that that's what it came down to - our attitude in defence is the reason we won."