Postecoglou's troubled side trailed to Hugo Ekitike's early goal in north London, but Pedro Porro hauled them level before half-time. Tottenham laid seige to the Frankfurt goal in the second half but couldn't find a winner after hitting the woodwork twice.
The result means under-fire Tottenham boss Postecoglou must mastermind a memorable victory in the second leg in Germany on April 17 to keep alive his hopes of winning the club's first trophy since the 2008 League Cup. The winner of the tie will face Bodo/Glimt or Lazio in the semi-finals in May, with the Norwegian club taking a 2-0 lead into the second leg against the Italians.
Postecoglou brashly claimed earlier this season that he always wins a trophy in his second campaign, a statement that has made him a hostage to fortune throughout Tottenham's turbulent run.