Leipzig, who would consider their forthcoming opponents a major top four rival this season, will hope to return to winning ways after drawing against FC Koln last time out.
Match preview
Indeed, although Leipzig's goalless draw away to Koln extended their unbeaten run to an astonishing 18 matches in all competitions, it did mean that they lost ground on Bayern Munich, Union Berlin and Borussia Dortmund above them in the table, while allowing Eintracht Frankfurt to move within one point of them.
In a scrappy encounter which featured more yellow cards than corners, with neither side even hitting double figures in terms of total shots, Marco Rose's side could not find the crucial breakthrough despite preventing the hosts from registering a single shot on target.
Overall, though, Die Roten Bulen are clearly heading on the right track under Rose. After replacing Domenico Tedesco in September, Rose lost two of his first three games in charge, but he since boasts an incredibly impressive unbeaten record of 14 wins and four draws in all competitions.
That impressive run of form means they have a quarter-final tie in the DFB-Pokal to look forward to later this season, after they have faced Pep Guardiola's Manchester City in the last-16 of the Champions League later this month.
While securing a fifth successive top four finish will be Rose's main priority this season, the 46-year-old may have half an eye on making up the four points between Bayern and his side between now and May, but they will need to win matches against rivals such as Union Berlin if winning the Bundesliga is to be a realistic possibility.
Having finished just one point behind Leipzig to narrowly miss out on qualifying for the Champions League for the first time in their history last season, Union Berlin will certainly have flagged Saturday's fixture as a major signpost in their season.
Urs Fischer's side have already beaten Leipzig once this season with a 2-1 victory at Stadion An der Alten Forsterei in August, although that was prior to Rose's appointment and their subsequent significant upturn in results.
Die Eisernen can expect a much tougher match this weekend, then, especially with it being away from home. However, having returned from the World Cup to win all five of their matches in all competitions, they look determined to go at least one better than the last campaign and secure a top four finish.
Like their forthcoming opponents, Union Berlin remain in Europe - with a last-32 tie against Ajax in the Europa League taking place this month - while they have a good chance of winning the DFB-Pokal for the first time in their history after beating Hoffenheim last week.
Given the disparity in resources and big game experience between the two clubs, Fischer may be content if his side can avoid defeat in Leipzig this weekend, although with only three draws in 19 league games to their name so far this season, sharing the spoils does not appear to be on the agenda for his high-flying team.
RB Leipzig Bundesliga form:
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RB Leipzig form (all competitions):
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Union Berlin Bundesliga form:
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Union Berlin form (all competitions):
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Team News
Leipzig will remain without two of their key forwards in the shape of Dani Olmo and Christopher Nkunku, who are likely to be sidelined for at least a few more weeks with hamstring and knee injuries respectively.
Rose's first-choice goalkeeper Peter Gulasci is expected to miss the rest of the season with an ACL injury, with Janis Blaswich continuing to deputise to good effect, but Abdou Diallo is nearing a return from a knee issue.
Having seen his side struggle for offensive fluidity after switching to a 3-4-3 formation against Koln, the former Dortmund boss could restore Emil Forsberg to his starting XI at the expense of a defender against Union Berlin, who are likely to sit deep and look to counter-attack for the most part.
After welcoming Morten Thorsby back to first-team action from the substitutes' bench during their 2-1 win against Mainz 05 last weekend, Andras Schafer's foot injury is the only availability issue restricting Fischer's selection at present.
Thorsby and Aissa Laidouni, who joined the capital-based side from Ferencvaros in January after an impressive World Cup with Tunisia, could be fighting for a spot in central midfield, with Paul Seguin likely to make way.
Despite scoring the decisive late winner against Mainz, Jordan Siebatcheu may be used as an impact substitute once again after fially ending his goalscoring drought of 10 league games.
RB Leipzig possible starting lineup:
Blaswich; Klostermann, Orban, Gvardiol, Raum; Laimer, Haidara; Szoboszlai, Forsberg, Werner; Silva
Union Berlin possible starting lineup:
Ronnow; Doekhi, Knoche, Leite; Trimmel, Thorsby, Khedira, Haberer, Roussillon; Becker, Behrens
We say: RB Leipzig 1-1 Union Berlin
Both teams have amassed impressive unbeaten runs in recent weeks, and there is unlikely to be much splitting the two teams on Saturday, especially with Leipzig missing Olmo and Nkunku through injury.
As such, given the amount at stake in terms of their pursuits to finish in the top four, we can envisage both teams settling for a point should the match be heading in that direction.