Saints could be facing a back row shortage on Friday night after Tom Wood and Teimana Harrison were retained by England.
Wood, Harrison, Dylan Hartley and Courtney Lawes are among 24 players staying at Pennyhill Park ahead of Saturday’s showdown with Argentina at Twickenham.
England will name their matchday squad on Thursday, but in the meantime, Saints will be pondering their options.
If Calum Clark receives a ban at Wednesday night’s RFU disciplinary hearing - the flanker was cited on Monday for striking with his elbow during last Friday’s win at Worcester - Saints will be left short.
Sam Dickinson looks set to miss this week’s game against Newcastle Falcons after being forced off with a knee injury at Sixways.
And No.8 Louis Picamoles will also be absent as he is with the France squad preparing for their clash with New Zealand in Paris.
That means Saints could be without as many as five key back row forwards this week.
Jamie Gibson and Ben Nutley appear certain starters against the Falcons, with the other spot likely to be filled by one of Michael Paterson or Lewis Ludlam.
Paterson predominantly plays in the second row for Saints, but could move into the back row, with James Craig coming in at lock alongside Christian Day.
Craig has also done a job in the back row in the past, so that could be another option.
England squad to face Argentina: Forwards: Dan Cole (Leicester Tigers), Charlie Ewels (Bath Rugby), Jamie George (Saracens), Teimana Harrison (Saints), Dylan Hartley (Saints), Nathan Hughes (Wasps), George Kruis (Saracens), Courtney Lawes (Saints), Joe Marler (Harlequins), Chris Robshaw (Harlequins), Kyle Sinckler (Harlequins), Billy Vunipola (Saracens), Mako Vunipola (Saracens), Tom Wood (Saints); Backs: Mike Brown (Harlequins), Danny Care (Harlequins), Elliot Daly (Wasps), Owen Farrell (Saracens), George Ford (Bath Rugby), Jonathan Joseph (Bath Rugby), Jonny May (Gloucester Rugby), Henry Slade (Exeter Chiefs), Ben Te’o (Worcester Warriors), Ben Youngs (Leicester Tigers)