Jorge Sampaoli's under-performing team battled past Deportivo Alaves 1-0 to make it through to the last eight, while their hosts knocked holders Real Betis out on penalties.
Match preview
One would not be surprised to hear that one of Sevilla and Osasuna occupied seventh spot in the La Liga table while the other was languishing in 15th, but it is not the serial Europa League-winning visitors who are making a charge for the continental spots this time around.
The sterling work of Jagoba Arrasate is certainly not going unnoticed, as Osasuna went behind twice to Copa del Rey holders Real Betis in their last-16 clash, and twice they responded to force a nervy penalty shootout, where Sergio Canales and Guido Rodriguez fluffed their lines as the champions' defence suffered a bitter end.
Osasuna will fear no foe after denying Betis the chance to win back-to-back crowns, but they were held to a disappointing 1-1 draw by basement side Elche in Sunday's La Liga match, where Chimy Avila's seventh goal of the season was cancelled out by Jose Angel Carmona.
Taking a break from their unexpected pursuit of European football, Osasuna are aiming to reach the semi-finals of the Copa del Rey for the first time since 2004-05 - where they finished as runners-up to Real Betis - and they have since suffered quarter-final eliminations in 2007 and 2010.
Still unbeaten since the turn of the year - winning three and drawing two of their contests in 2023 so far - Arrasate's side may even be considered by some as the favourites to secure a semi-final berth, but knockout specialists Sevilla are never to be counted out.
The appointment of Sampaoli has undoubtedly galvanised a Sevilla squad still facing the unfancied experience of a relegation dogfight, but Los Palanganas have developed a taste for winning during the festive period after falling well below their usual standards in the autumn months.
A solitary strike from Ivan Rakitic booked Sevilla's place in the last eight of the Copa del Rey in a narrow last-16 success over Deportivo Alaves, and the Croatian made lightning strike twice in the weekend's La Liga battle with Cadiz - scoring the game's only goal in a 1-0 victory.
Still separated from 18th-placed Real Valladolid by just one point, Sampaoli's men are aiming to qualify for the semi-finals of the Copa del Rey for the second time in three seasons, having progressed to the final four in 2020-21 before going down to Barcelona.
Boasting six wins from their last eight competitive matches in all tournaments, Los Palanganas have claimed all four of their Copa del Rey wins on the road so far this term, but Osasuna bested the visitors 2-1 in their opening La Liga contest of the season back in August.
Osasuna Copa del Rey form:
W
W
W
Osasuna form (all competitions):
L
W
D
W
W
D
Sevilla Copa del Rey form:
W
W
W
Sevilla form (all competitions):
D
W
W
L
W
W
Team News
Ever-present Osasuna midfielder Moi Gomez was forced off after 57 minutes of the weekend's draw with Elche with calf discomfort, although he is not thought to be nursing a serious problem and could potentially make an appearance in the quarter-final.
Nacho Vidal (hamstring) and Ruben Pena (quadriceps) continue to work individually and are unlikely to make their comebacks on Wednesday, while Avila will miss Osasuna's next La Liga game against Atletico Madrid through suspension but is available here.
Jon Moncayola and Aimar Oroz will compete to deputise for Gomez in the middle, and Arrasate could ring the changes up front as Kike Garcia, Ruben Garcia and Abde Ezzalzouli all pine for recalls.
As for Sevilla, Alex Telles, Jesus Corona and Marcao are no closer to making their comebacks from long-term injuries, but Thomas Delaney has rejoined team training as he steps up his recovery from a knee injury.
Argentinian attacker Papu Gomez is also nearing a return from an ankle sprain and could come into contention for Wednesday's game, where Marko Dmitrovic should displace Bono in between the sticks.
Osasuna possible starting lineup:
Herrera; Moreno, D. Garcia, U. Garcia, Cruz; Moncayola, Brasanac, Oroz; R. Garcia, Avila, Ezzalzouli
Sevilla possible starting lineup:
Dmitrovic; Bade, Rekik, Gudelj; Montiel, Jordan, Fernando, Lamela; Suso, Rakitic; En-Nesyri
We say: Osasuna 1-2 Sevilla (a.e.t)
Few Sevilla fans will be travelling to El Sadar with unbridled confidence, but a wealth of attacking options in reserve could ultimately make the difference for Sampaoli's steadily-improving crop.