Leinster and Ireland have received a boost with the news that centre Robbie Henshaw will train this week after returning from a hamstring injury sooner than expected.
The 25-year-old suffered the injury during the warm-up ahead of Ireland's November international against Argentina at the Aviva.
Captain Johnny Sexton, however, could miss Saturday's Champions Cup clash against Toulouse (RDS, 1pm) with a lower leg injury.
The out-half did not train last week and is not expected to take part in today's session.
"Johnny has had the problem for a few days now and he hasn't trained since picking it up in the Munster game but I would have no problem with playing Ross Byrne," Stuart Lancaster told reporters.
"Ross has showed himself capable in Europe last season and is probably the most improved player in our squad in the past 12 months."
Devin Toner is also a concern for the European outing.
At the start of December Leinster indicated that Henshaw would be out of action for eight weeks - a timeline that would have ruled him out of Ireland's opening Six Nations game against England on 2 February in Dublin.
Johnny Sexton rated 50/50 for the clash with Toulouse. He’s struggling with a lower leg injury and didn’t train last week— Paul O'Flynn (@OFlynnPaul) January 7, 2019
The holders are two points behind the French outfit in Pool A after four games.
Henshaw had endured a heavily injury-interrupted 2018.
He missed the three Six Nations victories over Wales, Scotland and England after damaging his shoulder in the act of scoring a try against Italy.
He did, however, feature in all three Tests in Ireland's 2-1 series victory over Australia in the summer.
Good news for Leinster & Ireland as Robbie Henshaw returns to training this week. Had been a doubt for 6 nations at one point.— Paul O'Flynn (@OFlynnPaul) January 7, 2019
"He's not going to train today but he's certainly moving along nicely," senior coach Lancaster told RTÉ Sport.
"He's getting close, if things go well today there's a good chance he could train tomorrow, which would put him in contention."