Jared Payne is yet to prove his fitness for Ireland's RBS 6 Nations clash with England, though Cian Healy and Mike Ross are ready for Saturday's Twickenham showdown.
Team manager Mick Kearney admitted Ireland are adopting a "wait and see" attitude to Ulster centre Payne's hamstring injury.
Ireland hope the 30-year-old will train fully on Tuesday, but have Ulster's uncapped battering ram centre Stuart McCloskey waiting in the wings as cover.
Fit-again Leinster props Healy and Ross are in line to boost Ireland's creaking scrum this weekend, while Johnny Sexton is also expected to feature after neck and ankle trouble.
"Jared Payne is continuing his rehab and the hope is that he will train fully tomorrow," said Ireland team manager Kearney.
"He did some running last week and will continue with that rehab today.
"It's a bit of a wait and see for him. I'd say the expectation is that he will train fully tomorrow, so we'll know a little more by this time tomorrow."
Leinster front-rowers Healy and Ross were named in Ireland's 34-man training squad on Monday morning to prepare for Saturday's Twickenham trip.
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Ireland have struggled at the scrum in both the 16-16 draw with Wales and 10-9 defeat in France, and will receive a clear boost from the return of two composed set-piece operators.
Loosehead Healy has recovered from knee surgery and tighthead Ross from hamstring trouble, with both featuring prominently in Leinster's 14-13 PRO12 victory over Cardiff on Saturday.
Now two of head coach Joe Schmidt's most trusted lieutenants can expect to take their place in Saturday's match squad, with Ireland still seeking their first win in this year's tournament.
The Six Nations' reigning double champions must claim a first win at Twickenham since 2010 to stand any chance whatsoever of securing an unprecedented third title in succession.
"Cian (Healy) and Mike (Ross) both joined the squad today," said Kearney.
"Tadhg Furlong has got that thigh injury and James Cronin has been allowed back to his province.
"I think they're pretty well there. They both participated in Leinster's last two games and both got a significant amount of game-time at the weekend against Cardiff.
"So they're in, fully fit and available for selection."
Lock Dave Foley has replaced Mike McCarthy, sidelined with concussion, Jordi Murphy slots in for hamstring injury victim Sean O'Brien and Ulster's Craig Gilroy offsets Dave Kearney's absence through shoulder trouble.
Keith Earls has been passed fit after missing the defeat in France with concussion, while Simon Zebo was expected back in full training on Monday after knee trouble.
Team manager Kearney described Sexton as "absolutely fine" following the neck problem suffered in the 10-9 defeat in France that head coach Schmidt described as a "whiplash injury".
Sexton trudged off in the closing stages of Ireland's second-round loss in Paris on Saturday, February 13.
The Leinster playmaker returned to full training last week, only to roll his ankle on Friday, but has since also recovered from that minor complaint.
"Johnny Sexton rolled his ankle last Friday and sat out the remainder of the session as a precaution," said Kearney.
"He's very good. He was taken out of the session on Friday purely as a precaution.
"He's in and will train fully this afternoon."
