Very little is known about the nature or extent of Owen Williams' injury, sustained whilst playing for Cardiff Blues against Asia Pacific Dragons in the World Club 10s on Sunday.
The Blues released a statement yesterday, saying: "Owen Williams is to remain in hospital in Singapore after sustaining an injury at the World Club 10s. Cardiff Blues will issue further updates when they are available."
Blues teammate Macauley Cook also tweeted yesterday to say he was at the hospital with Williams, waiting for his family to arrive.
The WRU said 22-year-old Williams has not travelled home with the rest of the Blues squad.
More top news
John Atkinson has resigned - but insists that his decision is about workload and nothing to do with recent problems within the Welsh party.
Amelia's mum Sarah Jones described how her dad was "panicking" when he told her the baby was "not breathing".
Former rugby star Ian Gough has won an assault appeal against former Miss Wales and ex-girlfriend Sophia Cahill.