Champions Cliftonville will continue their quest for a first home league win of the season when they host Dungannon Swifts at Solitude on Saturday.
The Reds have won just three of their first eight games, all away from home.
Despite a stuttering start to the defence of their title, Tommy Breslin's side lie just one point behind the four clubs at the summit of the table.
Portadown are top on goal difference, followed by Glenavon, Ballymena United and Linfield, who all have 14 points.
Cliftonville goalkeeper Conor Devlin remains sidelined with a shoulder injury, while defender Marc Smyth is a couple of weeks away from returning to first team action.
In addition, midfielder Ryan Catney has not trained for over a week since injuring his back.
The Swifts will be without Ryan Harpur, Cameron Grieve, Matt Hazley, Josh Barton and Abiola Sansui for the trip to north Belfast.
Buoyed by last week's derby win at Glenavon, Ronnie McFall's Ports will hope to see off the challenge of Ballinamallard United at Shamrock Park, despite still being without injured striker Gary Twigg.
Ballymena travel to Ballycastle Road to face derby rivals Coleraine without suspended skipper Allan Jenkins, who was sent-off for the second time this season in last week's eventful 2-2 draw with Glentoran.
Sky Blues' defender Davy Munster is expected to be ruled out for six weeks after fracturing a bone in his foot, but David Cushley is available again.
Coleraine boss Oran Kearney has Joe McNeill serving a suspension, while there are injury doubts over Ryan McIlmoyle and Paul Owens.
Linfield pair Andy Waterworth and Sean Ward continue their return to full fitness after injury and the duo are the only major injury concerns for Blues' manager Warren Feeney ahead of the visit of Glenavon to Windsor Park.
Glenavon are without Rhys Marshall, Eoin Bradley, Ciaran Martyn and Kyle Neill through injury, but William Murphy, Andy McGrory and James Singleton return.
Seventh-placed Institute are missing midfielder Michael McCrudden, who has a back complaint, while Cormac Burke will be assessed before the visit of Glentoran to Drumahoe as he struggles to shake off a hamstring problem.
Glens manager Eddie Pattesron has doubts over defensive duo Jay Magee and Barry Holland.
Warrenpoint entertain Crusaders but must plan without goalkeeper Johnny Parr, midfielders Ruairi Devlin and Stephen Hughes, and striker Timmy Grant.
The Crues have Paul Heatley sitting out the second half of his two-match suspension, while Josh Robinson is a concern with a hamstring injury.
Defender Craig McClean and midfielder Declan Caddell also face late fitness tests after playing 90 minutes for the reserves in midweek.
Irish Premiership fixtures - Saturday 20 September - 15:00 BST kick-offs
Cliftonville v Dungannon Swifts
Coleraine v Ballymena Utd
Institute v Glentoran
Linfield v Glenavon
Portadown v Ballinamallard Utd
Warrenpoint Town v Crusaders