Ireland hooker Rory Best has responded well to treatment on his shoulder but remains doubtful to face Wales in Saturday's World Cup quarter-final.
Best has been in rehabilitation since spraining his AC joint during Sunday's 36-6 victory over Italy at Otago Stadium.
Ireland are giving the Ulster front row, who has been in outstanding form, every chance to prove his fitness and have yet to rule him out of the World Cup.
"The medical team's worked hard with Rory over the last 24 hours. He's reacted well and we're very pleased with the response," said assistant coach Mark Tainton.
"He's not totally ruled out but his chances at the moment are long.
"He's doubtful for this weekend but has not been ruled out of the competition."
A replacement for Best has yet to be summoned to New Zealand and with Ireland due to name their side to face Wales in the early hours of Wednesday morning, time is running out.
If he fails to recover, Sean Cronin will start with Damien Varley promoted to the bench.
Munster hooker Michael Sherry has been summoned to New Zealand as precautionary cover for Best, who remains an official member of the World Cup squad.
"Rory Best is still progressing with his rehabilitation and while he is still rated doubtful for Wales, we felt it prudent to bring Mike down to New Zealand as precautionary cover," said manager Paul McNaughton. "We expect Mike to arrive in New Zealand on Thursday."