Wakefield captain and stand-off Jacob Miller went off in the defeat to St Helens with a knee injury.
Miller, 28, is a key player for Chris Chester, who was already missing seven players through injury for the game at the Totally Wicked Stadium, which they lost 34-6.
The coach said in his post-match press conference: “It doesn’t look great to be honest.
“We’re hopeful it’s just his medial ligament and, if it is, we’re looking at four to six weeks.
“We should have Max Jowitt back next week to cover that but these are challenging times at the minute.”
Wakefield have lost their opening three Super League games, and travel to Hull FC next week before hosting Catalans the following week in their first home game.