Ashton played 51 minutes against France before he was replaced by Jack Nowell, who is now poised to fill the vacancy for the potential title decider at Cardiff's Principality Stadium next Saturday.
England prop Mako Vunipola was ruled out of the championship on Tuesday with an ankle injury while lock Maro Itoje remains unavailable with a knee issue.
Coach Eddie Jones has called up 33 players to continue preparations for the Wales encounter.
Full squad:
Forwards
Dan Cole (Leicester Tigers), Luke Cowan-Dickie (Exeter Chiefs), Tom Curry (Sale Sharks), Ben Earl (Saracens), Charlie Ewels (Bath Rugby), Ellis Genge (Leicester Tigers), Jamie George (Saracens), Alec Hepburn (Exeter Chiefs), Nathan Hughes (Wasps)George Kruis (Saracens), Joe Launchbury (Wasps), Courtney Lawes (Northampton Saints), Ben Moon (Exeter Chiefs), Brad Shields (Wasps), Kyle Sinckler (Harlequins), Jack Singleton (Worcester Warriors), Billy Vunipola (Saracens), Harry Williams (Exeter Chiefs), Mark Wilson (Newcastle Falcons).
Backs
Mike Brown (Harlequins), Joe Cokanasiga (Bath Rugby), Elliot Daly (Wasps), Ollie Devoto (Exeter Chiefs), Owen Farrell (Saracens), George Ford (Leicester Tigers), Jonny May (Leicester Tigers), Jack Nowell (Exeter Chiefs), Dan Robson (Wasps), Henry Slade (Exeter Chiefs), Ben Te’o (Worcester Warriors), Ollie Thorley (Gloucester Rugby), Manu Tuilagi (Leicester Tigers), Ben Youngs (Leicester Tigers).
(Reporting by Hardik Vyas in Bengaluru; Editing by Christian Radnedge)
