Great Britain winger Ryan Hall dislocated his knee in the 12-8 loss to New Zealand in Auckland on Saturday, said head coach Wayne Bennett.
Hall, 31, had major knee surgery in 2018 and played only six NRL games for Sydney Roosters last season.
"I think he's dislocated his knee which he did earlier in the season," said Bennett. "It's gone back in but it did come out, so he said."
Hall and Jermaine McGillvary were the only two wingers named in the squad.
Asked if he would consider drafting in St Helens and Wales man Regan Grace, Bennett said he was unsure if he would be able add extra players to the touring party.
Wigan centre Oliver Gildart has already been ruled out for the rest of the tour with a shoulder injury sustained against Tonga Invitational XIII on 26 October, while St Helens prop Luke Thompson may not feature again after hurting his rib in the same match.
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'We're on the up,' says Bennett
Saturday's defeat by the Kiwis followed a similar pattern to Great Britain's 14-6 loss to the Tongans seven days earlier.
After falling 12-2 down, Daryl Clark's try brought the visitors to within four points but they could not complete a comeback.
Bennett said he would "not lose any sleep" over his side's lack of tries so far, with just two scored in their first two matches.
"The opposition only scored two as well," said the Australian. "The bottom line is no one is scoring a lot of tries.
"Last week we didn't make any opportunities to score tries, today we had opportunities to score tries so that's the difference.
"We're on the up, we're not going backwards and we played a quality team out there today.
"It was a tight game, there was nothing in it all afternoon," he added. "We probably should have had two tries in the last five minutes but we didn't get them and they managed to keep their nose in front."