Whoever prevails at the City Ground on Tuesday night will square off against Huddersfield Town or Luton Town at Wembley Stadium later this month.
Heading into Saturday's encounter in Yorkshire, Steve Cooper would have had doubts over whether Forest had lost some of their momentum having ended the regular campaign with two away fixtures without success.
Sander Berge's effort in added-on time has kept this tie very much alive, but Forest will be more than satisfied that they are returning to their fortress with a lead.
As it stands, their home winning streak stands at seven matches, scoring a total of 22 goals in the process, and they are statistics which highlight the size of the task in front of Sheffield United.
Johnson's 71st-minute goal at the weekend has taken him to 17 strikes for the Championship this campaign, the Wales international having previously gone four games without finding the back of the net before his late penalty versus Hull City on the final day.
If Sheffield United boss Paul Heckingbottom is going to cling onto a certain statistic, it will be that Forest have now gone four games without keeping a clean sheet.
At the same time, the Blades have scored in their last six outings, and there will be genuine belief that they can upset the odds when the action gets underway.
That said, Heckingbottom will feel relieved that the tie did not get away from his players at the weekend, particularly having conceded as early as the 10th minute.
Sheffield United's away return is in sharp contrast to Forest's home record, the Yorkshire side's only success in seven trips coming in their final regular contest at Queens Park Rangers.
Forest were boosted at the weekend as Keinan Davis made his return from a hamstring injury, getting over quarter-of-an-hour under his belt.
However, the Aston Villa loanee will remain on the substitutes' bench with Cooper almost certainly sticking with the same side from Saturday.
While Heckingbottom will also make minimal alterations to his Sheffield United XI, he may take the opportunity to bring in George Baldock at right wing-back.
The back three is expected to stay the same, but veteran forward Sharp is unlikely to make his return from a calf injury.
Nottingham Forest possible starting lineup:
Samba; Worrall, Cook, McKenna; Spence, Yates, Garner, Colback; Zinckernagel; Johnson, Surridge
Sheffield United possible starting lineup:
Foderingham; Basham, Egan, Robinson; Baldock, Norwood, Fleck, Stevens; Berge; Gibbs-White, Ndiaye
We say: Nottingham Forest 2-1 Sheffield United (Nottingham Forest to win 4-2 on aggregate)
With a late goal having kept Sheffield United in the tie, they will be optimistic about building further momentum during the early stages on Tuesday night. However, we simply cannot back against Forest getting the job done at the City Ground, leading us to predict another hard-fought victory for the East Midlands outfit.
For additional data used by our team to analyse our suggested result please click here.