The first fixture in the Netherlands ended goalless, and the domestic form of each team means that there will be optimism ahead of Thursday's clash at Stadion An der Alten Forsterei.
Match preview
Such has been the rise of Union Berlin that there is now disappointment if they draw any fixture, even when they are facing European giants such as Ajax.
That was particularly the case in the first leg with the German outfit having a goal disallowed by VAR, preventing them from returning home with a narrow lead.
Nevertheless, Urs Fischer's team remain as the favourites to progress, even if they were held to a surprise 0-0 draw at home to bottom-placed Schalke 04 at the weekend.
Had they won that encounter, Union Berlin would be sitting at the top of the Bundesliga standings, and Fischer needs to find a way to lift his side after that frustrating 90 minutes.
On a more positive note, Union Berlin are unbeaten in 10 home league fixtures during 2022-23, their only defeat on familiar territory this season coming against Union SG back on September 8.
From Ajax's perspective, they have been average by their own high standards this campaign, particularly on the domestic front, but this is a team that remains unbeaten in 13 matches in all competitions.
Since Johnny Heitinga's promotion to interim boss, he has overseen five victories in the Eredivisie, moving Ajax to within three points of leaders Feyenoord.
Another four goals were scored at the weekend, Ajax thrashing Sparta Rotterdam with a clean sheet to boot, and just one strike has been conceded in their last five fixtures.
With both teams boasting strong defensive records, this game has the potential to be decided by small margins, yet Heitinga and his players will recognise that their opponents' level dropped off at the weekend when they had the chance to sit above Bayern Munich.
Union Berlin Europa League form:
L
W
W
W
W
D
Union Berlin form (all competitions):
W
W
W
W
D
D
Ajax Europa League form:
D
Ajax form (all competitions):
W
W
W
W
D
W
Team News
Union Berlin will be able to recall Christopher Trimmel and Janik Haberer after they sat out the first leg through suspension.
While Trimmel may have to make do with a spot on the substitutes' bench due to the form of Josip Juranovic, Haberer may get the nod ahead of Morten Thorsby.
With Union Berlin having drawn a blank in the last two matches, Jordan Siebatcheu is in contention for a recall, but Diogo Leite will need to be assessed due to illness.
Although Heitinga is likely to line up with a similar Ajax XI to the one which started last week, Davy Klaassen is an option in central midfield.
Brian Brobbey will also come into the thinking of Heitinga, but he is more likely to remain among the replacements.
Union Berlin possible starting lineup:
Ronnow; Doekhi, Knoche, Leite; Juranovic, Laidouni, Khedira, Haberer, Roussillon; Behrens, Becker
Ajax possible starting lineup:
Rulli; Rensch, Timber, Bassey, Wijndal; Alvarez, Taylor; Berghuis, Kudus, Bergwijn; Tadic
We say: Union Berlin 2-1 Ajax
With Ajax scoring goals for fun on the domestic front, they will believe that it can be transferred over to continental action. However, Union Berlin are stronger than any team in the Eredivisie, and we feel that will show as they edge their way through to the last 16.
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