The 35-year-old - who hasn't featured in the last seven games - picked up a groin strain in the midweek reserve defeat to Southend and is set to miss the trip to Wales.
Gray will stick with the in-form trio of captain Chris Doig, Mark Hughes and on-loan Reading teenager Alex Pearce at the back with Australian defender Pedj Bojic favourite to take Dyche's place on the bench.
The 22-year-old has been out since January with a hernia problem which required surgery but came through the full 90 minutes of the reserve game and should be in Gray's 16.
Fellow defender Brett Johnson played 45 minutes against the Shrimpers' second string as he steps up his return from a hamstring injury but midfielder Joe Burnell remains some weeks short of a return from his ankle injury.
Ryan Gilligan will be hoping to keep his place in the starting line-up after excelling in place of Sam Aiston at Bradford last Saturday while James Hunt will again battle veteran Ian Taylor for a place in midfield.
Striker James Quinn has joined leaders Scunthorpe on loan until the end of the season but doctor Kenny Deuchar - who was replaced after complaining of blurred vision in the aftermath of his late winner at Valley Parade - has declared himself fully fit as Gray's side look for their fifth win in six games.
Reading striker Simon Cox will also be in the squad after signing on loan.
Swansea boss Roberto Martinez will hand a debut to on-loan Hull striker Darryl Duffy.
The 22-year-old former Rangers and Falkirk player has joined on loan until the end of the season and could go straight into the starting line-up.
Martinez needed to bolster his attacking options as Lee Trundle is suspended while Bayo Akinfenwa has been ruled out for the season with a broken leg.
Duffy's arrival has given the Spaniard an extra option with Pawel Abbott and young Chris Jones the other strikers on board.
Duffy said: "Swansea is a massive club which is going in the right direction and it's a new challenge to come here, and then hopefully go back to Hull stronger than ever next season."
However, Darren Way (shin), Garry Monk (knee), Owain Tudur Jones (knee) and Steve Watt (shoulder) are all certain absentees.