Leading try scorer Adam Swift will miss Saints’ final home fixture of 2016 against Wakefield Trinity Wildcats on Friday.
The fleet-footed winger, who has successfully crossed the whitewash 17 times in 21 appearances this season, is ruled out through concussion after being substituted in Sunday’s 21-8 Super 8s victory at Widnes.
Prop forward Greg Richard suffered a similar injury in the same match and he, too, will be an absentee.
Head coach Keiron Cunningham also left Jonny Lomax on the side lines at the Select Security Stadium but that was more of a precautionary measure than anything else.
The in-form full back is fully fit and available for selection but Cunningham may decide to rest him ahead of the sudden death Super League semi-final showdowns.
Saints will name their squad tomorrow afternoon (Wednesday) and there is an outside chance that centre Mark Percival, who has missed the last four matches due to a leg injury, will be back in contention.
Joe Greenwood will also be available for selection despite being charged with Grade A punching after Sunday’s game at Widnes where he was shown a yellow card.
He had an early guilty plea available - an option which the club exercised - and the 23-year-old is, therefore, available to play against the Wildcats.
Meanwhile, three of Saints’ talented youngsters, Morgan Knowles, Calvin Wellington and Regan Grace, have been named in the 29-strong train-on squad for Wales’ 2017 Rugby League World Cup qualifiers this autumn.