England must enter their seismic Guinness Six Nations clash against Ireland without their first choice inside centre after Ben Te'o suffered a side strain.
Te'o was set to start the opener in Dublin only for injury to strike during training on Monday, paving the way for Manu Tuilagi to be restored to the midfield against Joe Schmidt's Grand Slam holders.
In an additional blow, blindside flanker Brad Shields has failed to recover from his own side strain to ensure Mark Wilson will continue in the back row.
Te'o's absence points to a significant overhaul of the original plan with Tuilagi's power present at outside centre and George Ford and Owen Farrell restored as twin playmakers.
"Manu's been looking brilliant. You've seen some of his Champions Cup performances – for example against Scarlets at Welford Road," Hatley said.
"Manu's just got better and better and better as he's put games together. He's trained exceptionally well in the midfield for us. He's in a really good space.
"He's a physical player and guys like playing alongside blokes like that. He definitely has a positive effect."
Wilson, who is poised to deputise for Shields, was named England's player of the series last autumn with three superb appearances at number eight and one at openside flanker propelling him into World Cup contention.
The 29-year-old, who recently recovered from a shoulder injury, plays most of
his club rugby at Newcastle in the number six jersey.
England 25-man training squad retained in Portugal:
Forwards: L Cowan-Dickie (Exeter Chiefs), T Curry (Sale Sharks), E Genge (Leicester Tigers), J George (Saracens), N Hughes (Wasps), M Itoje (Saracens), G Kruis (Saracens), J Launchbury (Wasps), C Lawes (Northampton Saints), K Sinckler (Harlequins), B Vunipola (Saracens), M Vunipola (Saracens), H Williams (Exeter Chiefs), M Wilson (Newcastle Falcons).
Backs: C Ashton (Sale Sharks), M Brown (Harlequins), E Daly (Wasps), O Farrell (Saracens, capt), G Ford (Leicester Tigers), J May (Leicester Tigers), J Nowell (Exeter Chiefs), D Robson (Wasps), H Slade (Exeter Chiefs), M Tuilagi (Leicester Tigers), B Youngs (Leicester Tigers).