Inaki Williams scored in second-half stoppage time to earn Athletic Club a dramatic 1-0 victory over Barcelona in the 2019/20 Copa del Rey quarter-finals on Thursday night at San Mames.

In a Copa del Rey that has had its fair share of drama, this Thursday night won't soon be forgotten with both Real Madrid and Barcelona being ushered out of the Copa by a pair of Basque sides.

Just like in their league fixture to open the season back in August, Athletic would leave Barcelona staring in disbelief with a late goal, as a Williams header sent San Mames into pandemonium and punched Athletic's ticket to the Copa semi-finals.

Barcelona head coach Quique Setien opted for more of a 4-4-2, which meant only room for two players up front and they would be Ansu Fati and Lionel Messi, resulting in a place on the bench for Antoine Griezmann. Sergi Roberto was slotted into midfield, while Nelson Semedo started at right-back.

As always when Barcelona are in town, the crowd at San Mames roared with every chance, every ball won and every challenge administered by their team. It was back and forth in the first half-hour, with Ansu Fati and Messi having chances to open the scoring.

READ ALSO:

Eric Abidal To Keep His Job At Barcelona Despite Messi Criticism

Meanwhile, a lapse from Barcelona goalkeeper Marc-Andre ter Stegen gifted Athletic their first scoring opportunity, but Dani Garcia rushed his shot and missed over the crossbar.

Things stayed razor-thin going into the second half, with chances few and far between. Right after Frenkie de Jong was shown a yellow for diving in the area after a surgical pass from Messi, Setien made his first change, with Ansu Fati making way for Antoine Griezmann.

The match began to open up in Barcelona's favour and Setien looked to add more punch in midfield by bringing on Arthur Melo for Ivan Rakitic. Seconds after Arthur's entrance onto the pitch, Sergi Roberto picked out Griezmann, who had a clean look at goal, but Athletic goalkeeper Unai Simon made a big save.

Athletic boss Gaizka Garitano countered by bringing on the old lion himself and renowned Barcelona killer Aritz Aduriz for Iker Muniain. But Barcelona had other worries, namely an injury to Gerard Pique, so Samuel Umtiti was called upon to replace the veteran centre-back.

Barcelona kept poking and prodding in search of a late winner, and with minutes remaining it was all there for Messi to get the winner off a pass from Arthur, yet Unai Simon again came up with the stop, much to the dismay of the frustrated Argentine.

Just when it looked like the two sides would have to settle matters in extra time, Athletic would once again land a fatal blow on the Catalans in stoppage time, as Ibai Gomez whipped in a cross that Williams met with a glancing header that skipped past Ter Stegen and into net for the dramatic 1-0 victory.