Dragons five-eighth Gareth Widdop's strong form at fullback for England may sway coach Paul McGregor.

St George Illawarra Dragons captain Gareth Widdop is expected to start next season at five-eighth but coach Paul McGregor refuses to rule out a positional switch in light of the Englishman's starring role at fullback during the World Cup.

Widdop has again been named in England's No.1 jersey for Saturday's semi-final against Tonga in Auckland after being used in that position for the past three matches following the injury suffered by Jonny Lomax against Lebanon.

Lomax has recovered but has been unable to regain the position from Widdop, who is second for try assists at the World Cup with five. Fiji centre and former Dragons team-mate Taane Milne leads that category with seven.

"Gareth is doing what his team needs him to do and he is playing really well," McGregor said.

"His talent is bottomless, I have said that all along. He has got competitive fight, he has got a great footy IQ and he has got a high threshold for pain – he puts his body where other people don't. He is a class player, so he is a doing a good job for the team."

McGregor said Widdop, who has started just six of his 163 NRL matches in the No.1 jersey and has not played in the position since 2012, had the ability to be one of the best fullbacks in the NRL. 

However, his best role for the Dragons is still likely to be at five-eighth, where he would play alongside star signing and Kangaroos squad member Ben Hunt.

"Ben Hunt is coming which is great for Gareth as he has got a partner in crime in the halves," McGregor said. "But Gareth has that ability to play anywhere he is needed to play for the team.

"It is the same with Ben Hunt, he is going to be our No.7 but he can also play No.9. It is a great thing for the squad to have these guys who are that skilled they can play multiple positions."

With Josh Dugan moving to Cronulla, the St George Illawarra No.1 jersey is up for grabs and McGregor is yet to decide who will take over the role at the start of the season.

"Potentially I have a number of guys who can play fullback and Gareth is one of those," he said.

"Young Matt Dufty finished the year strong, Kurt Mann is a great half/fullback, young Zac Lomax is coming through, we've got Jai Field so there is a probably cast of thousands I could choose from but Gareth just adds to that."