Pablo Ibanez's gorgeous extra-time volley stunned Athletic Bilbao as Osasuna sealed their spot in the Copa del Rey final with a 1-1 draw at San Mames that secured a 2-1 aggregate win.

Jagoba Arrasate's men only held a slender 1-0 lead from last month's first leg in Pamplona, and for much of the match that looked unlikely to be enough.

Athletic deservedly levelled the aggregate score just after the half-hour, with Inaki Williams diverting Mikel Vesga's flick-on home from close range.

The Ghana international's younger brother Nico Williams seemed destined to put Athletic ahead in the tie during the second half, but the Spain winger wasted two glorious opportunities.

Athletic's profligacy coupled with Sergio Herrera's excellence between the posts ensured the game was extended by another 30 minutes.

Osasuna capitalised with just four minutes of extra time left, and in spectacular fashion, as Jon Moncayola's cross to the edge of the box was met by an exceptional controlled volley from Ibanez that left Julen Agirrezabala helpless.

Los Rojillos will face either Barcelona or Real Madrid – whose second leg is on Wednesday – in what will be just Osasuna's second Copa del Rey final ever.