Wakefield coach Chris Chester has revealed Wildcats captain Danny Kirmond is currently on a drip in hospital after his knee became infected.
Kirmond, who secured a vital 10-2 win against his former club Huddersfield only last Sunday, had to sit out Friday's 32-6 home defeat by Leeds, despite being initially named in Chester's 19-man squad.
"There's quite a bad swelling around the knee, which we thought was caused by a tear to the ligament but it turns out it's some kind of infection," Chester said.
"He went to A&E on Wednesday night and again on Thursday because he was in so much pain and he went back in hospital today to go on a drip. If that doesn't sort it out, then he'll need a little operation tomorrow."
The Wildcats were led by goalkicking scrum-half Liam Finn on Friday night as vice-captain Nick Scruton has also been sidelined with a groin injury.
Both Kirmond and Scruton look as if they will miss Trinity's next match, a Ladbrokes Challenge Cup quarter-final against Huddersfield at the John Smith's Stadium next Thursday, a game described by Chester as the club's biggest since 2008.