Basel book quarter-final of the Europa League against Shakhtar Donetsk by defeating Frankfurt in 1-0 win.
Playing before the coronavirus shutdown, the Swiss side held a three-goal lead from the first leg in March.
In search of an early lifeline, Frankfurt began brightly and Martin Hinteregger with a header came close to the center-back.
The visitors enjoyed a lot of possession but they could not find a way past Djordje Nikolic, the Basel goalkeeper.
The advancing keeper was approached by Basel midfielder Valentin Stocker with a fine run and chip, but Kostic cleared off the line.
In the 88th minute, Fabian Frei eventually ended the deadlock.
Basel 1- 0 Frankfurt
Goals: 1-0 Frei 88′
Yellow cards: Comert (B); Kohr (F), Chandler (F)
Basel: Nikolic, Widmer, Comert, Alderete, Petretta, Frei, Xhaka, Pululu, Ccampo, Stocker, Arthur
Frankfurt: Trapp, da Costa, Abraham, Hinteregger, N’Dicka, Kohr, Rode, Kostic, Silva, Kamada, Dost