The 19-year-old Wirtz, in top form since his return this year following a months-long injury break, fired in to cancel out Union’s lead through Victor Boniface in the 51st.

The result left the tie open ahead of next week’s return leg in Belgium but snapped Leverkusen’s six-game winning run across all competitions.

Union, in their maiden Europa League campaign, struck six minutes after the restart with Boniface finding space on the left, cutting into the box and whipping a shot past keeper Lukas Hradecky for his sixth European goal in nine games this season.

Xabi Alonso’s Leverkusen were in control for much of the second half but missed a golden chance to level when Jeremie Frimpong’s header from four metres out sailed wide of the post in the 78th. Wirtz did it better five minutes later.