The city rivals are separated by only one point heading into the match, with both teams still in outside contention of securing European football for next season.
Hertha were beaten 1-0 in the reverse fixture six months ago and are aiming to avoid back-to-back losses in the Berlin derby for the first time ever.
Sebastian Polter scored the only goal of the match for Union, who are enjoying an incredible maiden campaign in the German top flight.
Hertha are unbeaten in their last three games, meanwhile, with last Saturday's 3-0 win over Hoffenheim on their return to action moving them up to 11th, one place above Union.
Finishing sixth will be enough to earn a Europa League qualifying spot, but Hertha are eight points behind Wolfsburg and look likely to consolidate in mid-table.
It was the second-highest margin of victory for a Hertha coach in his first Bundesliga match, and now the aim will be to make it successive wins for the first time since December.
Union will have different ideas, of course, and Die Eisernen have been victorious in two of their last three Bundesliga away games, picking up more points (6) in those matches than they did in their opening 10 top-flight games (5).
However, Fischer's men have lost 2-1 in both of their previous Friday night games in the Bundesliga this season, most recently losing to Schalke 04 in November.
Union also failed to turn up in their first match back, producing a rather below-par display in last weekend's 2-0 home loss to league leaders Bayern Munich.
The visitors will have to show far more of an attacking edge if they are to come out on top on Friday evening and make a piece of Berlin derby history by doing the double.
Hertha Berlin's Bundesliga form: LWLDDW
Hertha Berlin's form (all competitions): LWLDDW
Union Berlin's Bundesliga form: WLWDLL
Union Berlin's form (all competitions): LWDLLL
Any further changes on the back of such a positive result would be surprising, so Peter Pekarik should continue at right-back after an impressive return to the side last time out.
As for Union, they are without suspended defender Keven Schlotterbeck for this huge derby showdown.
Eleven-goal top scorer Sebastian Andersson is also in line for a return to the side, having only been fit enough for a place on the bench for the loss to the reigning champions.
Hertha Berlin possible starting lineup:
Jarstein; Pekarik, Boyata, Torunarigha, Plattenhadt; Darida, Grujic; Lukebakio, Cunha, Mittelstadt; Ibisevic
Union Berlin possible starting lineup:
Gikiewicz; Friedrich, Hubner, Subotic; Trimmel, Gentner, Andrich, Lenz; Ingvartsen, Bulter; Andersson
We say: Hertha Berlin 1-1 Union Berlin
Not a great deal can be read into the form book prior to the coronavirus-enforced shutdown, but Hertha looked far better than Union in the two sides' first game back last weekend. There has been little to separate the Berlin rivals all season, though, and we are expecting them to cancel each other out on Friday.