Portadown defender Keith O'Hara is rated doubtful for the Carling Premiership title tussle with champions Linfield at Windsor Park.
O'Hara has a groin injury while Blues midfileder Michael Gault is set to return after a foot problem.
The pacesetting Ports are a point ahead of Linfield, who have a game in hand.
"We are in good form and we are determined to stay top, but we know just how hard this match will be," said Portadown manager Ronnie McFall.
The Ports defeated the Blues 2-0 at Shamrock Park in their previous league meeting last month.
"Saturday's game, put very simply, is massive," Linfield boss David Jeffrey told the club website.
"Our opponents have already beaten us this season. I was very clear that on the day we should have had at least a share of the points.
"It's no surprise to me to see Portadown where they are. I've said consistently that they will be up there challenging.
"For me they've been the perennial underachievers, simply because of the quality they have in their squad.
"We are looking to respond to our defeat against Glenavon in the League Cup. That was a night when we were very frustrated and we disappointingly exited on penalties from the competition.
"Here we have ourselves facing the league leaders, so there is no better motivation for our players."
Crusaders travel to Cliftonville in a north Belfast derby between the teams lying in third and fourth.
Crues skipper Coalin Coates is banned although Stephen McBride is back from a hamstring injury, while Reds defender John Convery is suspended.
Carrick Rangers pair Aaron Harmon (knee) and Tony Anderson (hamstring) are ruled out of the home game against Ballymena United, with Davy McAlinden (foot) a concern for boss Stephen Small.
United are missing injured trio Richard Vauls, Aaron Boyd and Rory Carson, while Liam Watson and Wayne Drummond are doubts and Jordan Baker returns from a calf strain.
Donegal Celtic go into the Suffolk Road game against Glenavon with key players Ryan Henderson, Stephen McAlorum, Paul McVeigh and Darren Murray back in the squad.
The Lurgan Blues are without the suspended Niall Henderson.
Lisburn Distillery's Philip Simpson remains out with a knee injury as the Whites prepare to face Coleraine at New Grosvenor.
Glentoran will move into the top four if they secure an away victory over Dungannon Swifts.
Saturday 22 October - 1500 BST
Carrick Rangers v Ballymena Utd
Cliftonville v Crusaders
Donegal Celtic v Glenavon
Dungannon Swifts v Glentoran
Linfield v Portadown
Lisburn Distillery v Coleraine