The Tykes will head into the match in eighth place in the League One table, while the Millers are trailing by five points in 14th position.
Match preview
Barnsley are sitting just one point outside the playoffs after winning six, drawing four and losing three of their 13 league matches.
The Tykes have proven to be a tough team to beat in recent league outings, having lost just one of their previous seven matches in the third tier (W3, D3).
Since losing to Huddersfield on October 5, Barnsley have gone on to win away league games against Blackpool and Shrewsbury Town on either side of a 2-2 home draw with Charlton Athletic.
Darrell Clarke's side have put their league campaign on hold for their last two matches, with Barnsley losing 3-1 in an EFL Trophy game against Doncaster Rovers, before they came out on the right side of the same scoreline in their recent FA Cup meeting with Port Vale.
Marc Roberts, Davis Keillor-Dunn and Adam Phillips all got on the scoresheet to set up a second-round tie against fellow League One side Bristol Rovers at Oakwell.
Incidentally, Barnsley have not won a home game since beating Bristol Rovers on September 9, leaving them without a win in four consecutive home matches ahead of Friday's clash with Rotherham.
After suffering relegation last season, Rotherham are struggling for consistency in their bid to secure an immediate return to the Championship.
Having won four, drawn five and lost five of their 14 matches, the Millers are currently six points adrift of the playoffs and six points above the relegation zone.
They recently experienced a three-game winless league run before they got back on track with a 2-0 victory over Steve Evans's former side Stevenage.
Unfortunately for the Millers, they were unable to back up that result in their recent FA Cup clash against Cheltenham Town, who ran out 3-1 winners at the New York Stadium to condemn Rotherham to their first round one exit since 2017-18.
They will be keen to offer a positive response in Friday's league fixture, but their hopes of claiming all three points may be tempered by the fact they have won just one of their eight competitive away games this season (D3, L4).
Rotherham are searching for their first competitive win over Barnsley since October 1982, while they have not won an away match against the Tykes since recording a 1-0 victory in a League Cup tie in August 1970
Barnsley League One form:
D
D
L
W
D
W
Barnsley form (all competitions):
L
W
D
W
L
W
Rotherham United League One form:
W
W
D
L
L
W
Rotherham United form (all competitions):
W
D
L
L
W
L
Team News
Barnsley will have to assess the fitness of forward Sam Cosgrove, who has sat out the last three matches with a back injury.
Phillips is pushing for a starting spot after he came off the bench to score from the penalty spot against Port Vale.
Keillor-Dunn will continue to provide one of the visitors' main attacking threats, having scored three goals in his last four appearances
As for the visitors, they will have to assess the fitness of Jonson Clarke-Harris, who has missed the last four matches with a hamstring issue.
Winger Joseph Hungbo could return to the Rotherham lineup after dropping down to the bench for the FA Cup defeat against Cheltenham.
Forward Sam Nombe is also pushing for a recall, and he could replace Jordan Hugill as the main centre-forward for Friday's fixture.
Barnsley possible starting lineup:
Slonina; De Gevigney, Earl, Roberts; O'Keeffe, Russell, Connell, Gent; Phillips; Keillor-Gunn, Humphrys
Rotherham United possible starting lineup:
Dawson; Rafferty, Humphreys, Jules, Bramall; Odoffin, Tiehi, Powell; Hungbo, Wilks, Nombe