He missed the 30-22 defeat by Scotland nine days ago because of a shoulder injury, having been recalled from the international wilderness to lead his country against England two weeks earlier.
"I am fine in myself, and more or less definite to make it," said Humphreys, before embarking on a three-day training camp with the Welsh squad in Tenby.
"In my own mind, I am 100% confident of being fit."
If Humphreys does not make it then Pontypridd hooker Mefin Davies will probably take over, with Wales coach Steve Hansen springing a major surprise on the bench.
Injuries to hooker Robin McBryde, Barry Williams, Andrew Lewis and latterly Gareth Williams - who started against the Scots - mean that 19-year-old unknown Huw Bennett could be promoted from obscurity.
Bennett, currently on Swansea's books, is highly-rated by Hansen who said: "He has got a bit of the x-factor about him.
"He is going to be a very good player in the future and he has been working with us now for most of the time over the last 12 months."