Despite enduring three consecutive ties going to extra-time ahead of the Copa del Rey semi-finals, Osasuna began the home leg of this final-four clash brightly, but struggled to create any significant chances in front of goal.
In turn, Athletic began to grow in confidence as the first half went on, and thought they had opened the scoring after the quarter-hour mark, when Iker Muniain’s shot was parried into the path of Iñaki Williams. The Ghanaian slotted in first time but he was deemed offside, keeping the scoreboard unaltered.
Athletic’s Muniain was beginning to dictate the play going forward by this point, but a lack of quality in front of goal again proved problematic, ensuring that the game would peter out into a goalless half-time scoreline.
But whatever Jagoba Arrasate said at the break worked wonders, as Los Rojillos took the lead less than three minutes after the restart.
A long ball up the pitch freed Abde Ezzalzouli down the left wing, and the Moroccan fired an ambitious effort across Julen Agirrezabala into the far corner, sending the El Sadar crowd wild.
Tempers were frayed in the dying minutes, with Ernesto Valverde’s men in particular becoming increasingly fraught as the seconds ticked by.
Yet, Raul Garcia had the composure to time a purposeful run well and come within inches of levelling the tie, but his header went narrowly wide of the post.
Osasuna took heed of that warning and held out for the victory, giving them a potentially precious lead going into next month’s second leg clash on April 4.