Osasuna was beaten in the 2004-2005 final by Real Betis, but boosted its chances of reaching the tournament's showpiece match for a second time with a home victory at Estadio El Sadar.

The first half was a scrappy affair, distinctly lacking in attacking quality as both teams struggled to put its stamp on the match.

But moments into the second half, a swift Osasuna counter ended with Abde charging into the box before unleashing a powerful drive into the bottom right corner.

Athletic's search for an equaliser never really got going, as they ended the match with only two shots on target and an xG (expected goals) of just 0.41.

Its best opportunity fell at the feet of substitute Gorka Guruzeta in the dying seconds, but his tame effort was comfortably saved by Sergio Herrera, and Athletic will have much work to do in the reverse leg at San Mames on April 4 if they are to keep its hopes of winning a 24th Copa del Rey alive.