N'Dicka's late header gave Frankfurt their first home win of the season amid a return to form in recent weeks. Frankfurt had an early goal ruled out for offside, but took a deserved lead through Djibril Sow on 22 minutes. The Swiss midfielder pounced on a poorly defended corner and rifled the ball in with a brilliant half-volley.
The home side had several chances to double the lead before half-time as they continued to pile pressure on an unsettled Union back line. Makoto Hasebe hit the bar with a header, while Filip Kostic, Rafael Borre and Kristijan Jakic all missed the target from close range.
They were made to rue the missed chances when Union equalised against the run of play on the hour mark. After a clear foul on Taiwo Awoniyi in the Frankfurt box, Max Kruse slotted in his second league goal of the season from the penalty spot.
Union seemed to have done enough to snatch a point, before N'Dicka rose in the box late in injury time to head home Kostic's cross and seal the three points for Frankfurt.