RLWC England vs Lebanon at the Sydney Football Stadium. Picture : NRL Photos/Gregg Porteous

Billy Slater has identified Gareth Widdop as England's danger man in the World Cup final and insists the Kangaroos won't be taking their eyes off his opposite number for a second in the attacking line.

Widdop was moved to fullback by coach Wayne Bennett during this campaign and it proved a masterstroke with the former five-eighth chiming in to the backline and creating opportunities for his supports ever since.

That purple patch of form does not surprise Slater one bit.

"Gareth always had this sort of potential," he said.

"He played number one when he was coming through the under-20s and when [Melbourne] won the competition in 2009 he was a key player. Then he won a premiership with us in 2012, so we all know what Gareth Widdop is capable of. He is probably their strike weapon and we need to know where he is at all times."

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Slater said Widdop had an incisive running game and was also a skilful passer of the football, making him doubly dangerous.

"So being aware of where Gareth is when they are attacking our tryline is probably a key for us," he said.

"That is a big indicator of where they are going to go.

"I have played a bit of footy with Gareth in Melbourne and he is a natural. So long as he has the ball in his hands he is going to be a danger."

Widdop said he hadn't played fullback for six or seven years before this tournament but had stored in his memory bank all the secrets of the position that he learned from Slater when they were at the Storm together.

"I learned a few things of Bill and hopefully those things I did learn I can use for the weekend's game," Widdop said.

"When I was coming through the 20s I was playing fullback so I worked really close with Bill.

"It has been good [at fullback] and the more I play there the more comfortable I feel."

While Slater will have his eye on Widdop, the reverse is also true.

England trained on Wednesday in the Brisbane rain and were rehearsing how they would defend the outside/inside play that Slater, Cameron Smith and Coper Cronk have mastered.

"That is one play those three boys have been doing together for the last 10 or 15 years," Widdop said.

"It is easy to watch it, but stopping it is going to be difficult.

"That is where we need to switch on, and for 80 minutes in this game, because they are going to throw all sorts of different things at us."

This article originally appeared on NRL.com.