Ireland remain "reasonably positive" over Robbie Henshaw's hamstring injury, though the centre is still expected to miss his nation's Rugby World Cup opener against Scotland.

Henshaw suffered the problem during a training session on Saturday, putting his participation in the tournament in jeopardy.

However, while unlikely to be fit to face Six Nations rivals Scotland in the Pool A fixture on Sunday in Yokohama, there is still hope the Leinster player can feature for Joe Schmidt's side.

"Robbie's looking very, very unlikely for this weekend obviously," Ireland scrum coach Greg Feek told the media.

"But we've just got back from training and still sorting things out, but I think it's reasonably positive in terms of what we saw.

"Some of these guys, day by day, week by week, they can improve dramatically as opposed to the average human. So we'll just take it like that at the moment.

"It's looking positive, so from here on in we'll just see how it goes in the next few days and then maybe reassess in the not too distant future."

Ireland tweeted confirmation that Henshaw will not be returning home early despite the setback.

Meanwhile, Joey Carbery trained fully on Monday and Keith Earls is likely to be back working with the rest of the squad later this week.

After facing the Scots, Ireland have fixtures against hosts Japan, Russia and Samoa in the group stage.