Unsurprisingly, Leverkusen dominated the first half, almost scoring inside the first minute. Jeremie Frimpong bombed forward from wing-back and made some space for himself in the box, before shooting just wide.
The hosts suffered a scare when Andrej Ilić had the ball in the net for Union, but his strike was disallowed for offside, much to the relief of the home crowd.
Xabi Alonso’s men continued to press for a half-time lead, as Patrik Schick also struck just past the post on the half-hour mark, but Die Werkself could not find a breakthrough, having registered just one shot on target.
Alonso introduced the fit-again Florian Wirtz early in the second half to try and change his team’s fortunes, and the German almost made an immediate impact when he fed Exequiel Palacios in the box, who forced Frederik Rønnow into a smart save.
Union provided a threat on the break in the face of the hosts’ dominance, with Lukas Hradecky equal to Lucas Tousart’s strike before substitute Benedict Hollerbach made it easier for the goalkeeper than it ought to have been when he hit straight into his grateful arms after being played in behind.
Leverkusen kept pushing as they looked to replicate their late winner against Heidenheim last time out, but fell short this time as they handed the onus to league leaders Bayern Munich, who could move eight points clear with victory in Der Klassiker.
Union boss Steffen Baumgart will be delighted with the point away from home against illustrious opposition, as any previous worries of relegation are now all but over, with Die Eisernen 12 points clear of the drop zone.
Flashscore Man of the Match: Leopold Querfeld (Union Berlin)