St Helens will be without Shannon McDonnell for the remainder of the Super League campaign, as the full-back requires surgery to rectify an Achilles injury.
The 27-year-old, who only returned to the club in April, sustained the damage late on in the Saints' narrow 25-24 defeat against Castleford Tigers last Thursday.
Head coach Keiron Cunningham has now revealed that McDonnell will undergo an operation, which is expected to see him out until the start of next season.
"We all feel for Shannon. He has a lot of friends at the club and we'll support him," Cunningham said via Twitter.
St Helens are currently second in the Super League table, sitting one point below leaders Leeds Rhinos.