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England stand-off Kevin Brown receives treatment during the win over Papua New Guinea

England v Tonga, World Cup semi-final Date: Saturday, 25 November, 05:00 GMT. Venue: Mount Smart Stadium, Auckland Coverage: BBC Two from 04:30, BBC Radio 5 live and live text commentary on BBC Sport.

England have named an unchanged team for Saturday's World Cup semi-final against Tonga but stand-off Kevin Brown will have to pass a series of tests before he can play.

He was knocked out during his team's 36-6 win over Papua New Guinea on Sunday and withdrawn at half-time.

If he is not passed fit to play Gareth Widdop is likely to move from full-back, with Jonny Lomax replacing him.

Fit-again Lomax and Scott Taylor have been brought into the reserve list.

They have replaced Stefan Ratchford and George Williams - and could yet figure in the final 17 if Brown fails his assessment or any players pick up injuries in training.

England are hoping to reach their first World Cup final since 1995 and the absence of Brown would be a blow to a side that has looked more solid and organised since he was brought in against France at the end of the group stage.

Brown was knocked out after colliding with an opponent 25 minutes into the quarter-final win in Melbourne but replays were not working in the stadium and the England team were unaware of the fact that he had been momentarily knocked unconscious.

An England player who was not in the matchday squad then spotted the incident on social media and informed the doctor, who withdrew Brown at half-time.

England coach Wayne Bennett said after Sunday's match that the concussion was rated category one, the lowest grading, and he was confident Brown would be cleared to play.

If Brown is passed fit then he will once again partner Luke Gale in the halves, with Widdop able to continue his impressive form at full-back.

Two changes for Tonga

England face a Tonga side that are unbeaten in the tournament - although they were given a real scare during their 24-22 quarter-final win over Lebanon on Saturday.

In many ways the surprise package of the competition, Tonga are unbeaten and claimed the notable scalp of New Zealand in the group stages - a result that placed them in the same half of the draw as England.

They are strengthened by the return of forwards Sio Siau Taukeiaho and Peni Terepo after they missed the win over Lebanon.

Several of the Tonga squad play for Super League clubs - including captain Sika Manu, who plays for Hull, and Catalans Dragons prop Sammy Moa.

"Sammy Moa and Sika Manu have been giving us a few tips about certain players," said hooker Siliva Havili.

"They say their threat will be all across the whole park. They have big outside backs and big forwards. We've just got to be up for it on Saturday."

In the other semi-final, favourites Australia's take on Fiji in Brisbane on Friday - with live text coverage of that match on the BBC website.

The only changes for the imperious Kangaroos from their 46-0 quarter-final win over Samoa are on their reserve list, with Tom Trbojevic and Josh Mansour replacing Cameron Munster and Ben Hunt.

There were emotional scenes in Wellington last weekend when Fiji pulled off a stunning 4-2 win over the Kiwis - and they are unchanged for what will undoubtedly be their biggest challenge so far.

Tournament rules state teams have to announce their 17-man squads on Tuesday but they also name a further four players on a reserve list and have the option of changing them up to 24 hours before the game.

England: G Widdop (St George Illawarra); J McGillvary (Huddersfield), K Watkins (Leeds), J Bateman (Wigan), R Hall (Leeds); K Brown (Warrington), L Gale (Castleford); C Hill (Warrington), J Hodgson (Canberra), J Graham (St George Illawarra), S Burgess (South Sydney), E Whitehead (Canberra), S O'Loughlin (Wigan, capt).

Interchange: A Walmsley (St Helens), T Burgess (South Sydney), B Currie (Warrington), J Roby (St Helens).

Tonga: W Hopoate (Canterbury Bulldogs); D Tupou (Sydney Roosters), M Jennings (Parramatta), K Hurrell (Gold Coast), D Fusitua (NZ Warriors); T Lolohea (Wests Tigers), M Hingano (NZ Warriors); A Fifita (Cronulla), S Havili (St George Illawarra 5/8), S Siua Taukeiaho (Sydney Roosters), M Ma'u (Parramatta), S Manu (Hull, capt), J Taumalolo (North Queensland).

Interchange: S Katoa (Penrith), P Terepo (Parramatta), T Pangai jnr (Brisbane), B Murdoch-Masila (Salford).