With 23 titles to their name, the Red and Whites are the second-most decorated side in the cup's history and will be looking to secure their first cup triumph since the 1983-84 campaign.
Match preview
Having seen off two lower division sides in their first two Copa del Rey games, Athletic Bilbao were put to the test in the round-of-32 when they were drawn against a more experienced Eibar side.
Bilbao kicked off their quest for a 24th cup title with an unconvincing 2-1 victory over amateur side Rubi on November 1, five weeks before claiming a more assured 3-0 victory over Crayon in Santander.
They passed the Eibar test with flying colours as they cruised to a 3-0 victory at the Municipal de Ipurua on January 7 courtesy of a first-half brace from Asier Villalibre and Iker Muniain's 33rd-minute strike.
Not only have Bilbao enjoyed a solid cup run, but they have also been on song in the La Liga, where they are on a four-game winning streak and are unbeaten in their last 10 outings, claiming seven wins and three draws since October's 1-0 loss at Barcelona.
The Red and Whites made it five consecutive wins across all competitions on Saturday when they edged out Real Sociedad 2-1 on home turf, a result which saw them move into third place in the league standings.
Tuesday's cup tie pits Ernesto Valverde's men against a more familiar foe in Alaves, against whom they are unbeaten in the last five meetings between the teams, claiming three draws and two wins, including a 2-0 victory in their La Liga clash back in September.
Bilbao enjoyed a smooth run to the Copa del Rey semi-finals last season, before suffering a 2-1 aggregate loss against Osasuna, with Pablo Ibanez scoring the all-important goal in the 119th minute of the second leg to send Los Rojillos through to the final.
Alaves, on the other hand, head into the midweek clash aiming to surpass last season's cup run as they suffered a round-of-16 exit last term following a 1-0 defeat at the hands of Sevilla.
Luis Garcia's side kicked off the campaign with a resounding 10-0 victory over Primera Autonomica outfit Deportivo Murcia on November 2, before claiming a narrow 1-0 win against Tarrassa FC in the second round.
Alaves scraped through the round-of-32 on January 6, when Carlos Benavidez netted the only goal off the game to see off Real Betis 1-0 at the Estadio de Mendizorroza and end their four-game winless run.
A 3-2 victory away to Sevilla in La Liga on Saturday was another result to prove the team's level of improvement since the winter break as El Glorioso have now moved five points clear of the relegation zone.
Having played out a 1-1 draw with Sociedad in their first game of 2024, Alaves have now gone three consecutive games without defeat across all competitions since the turn of the year — their joint-longest unbeaten run this season.
While the new year appears to have ushered in a change in fortune for Garcia's men, next up is a trip to the San Mames Stadium, where they have failed to win any of their last eight visits, losing four and picking up four draws since a 2-0 victory in November 2005.
Athletic Bilbao Copa del Rey form:
W
W
W
Athletic Bilbao form (all competitions):
D
W
W
W
W
W
Alaves Copa del Rey form:
W
W
W
Alaves form (all competitions):
L
L
L
D
W
W
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Team News
Bilbao will take to the pitch without experienced striker Inaki Williams, who is currently away with the Ghana national team at the ongoing Africa Cup of Nations.
On the injury front, Valverde will be unable to call upon the services of 33-year-old midfielder Dani Garcia, who has been sidelined since coming off with a thigh problem back in November.
Former Manchester United man Ander Herrera should come into the fold on Tuesday, replacing Spanish midfielder Inigo Ruiz de Galarreta, who was forced off injured midway through the second half at the weekend.
Alaves will also have to cope without the duo of Abdelkebir Abqar and Jesus Owono, who are currently at the Africa Cup of Nations with Morocco and Equatorial Guinea respectively.
Serbian defender Aleksandar Sedlar is also out of contention for Tuesday's game as he continues his long road to full fitness after suffering an ACL injury back in November.
Athletic Bilbao possible starting lineup:
Simon; Lekue, Vivian, Paredes, Berchiche; Herrera, Vesga; Berenguer, Sancet, N Williams; Guruzeta
Alaves possible starting lineup:
Sivera; Gorosabel, Tenaglia, Marin, Lopez; Guevara, Benavidez; Vicente, Guridi, Rioja; Garcia
We say: Athletic Bilbao 2-0 Alaves
While Alaves have put together a run for form to start the new year, they face their biggest challenge yet as they go up against a high-flying Bilbao side who have won their last five matches across all competitions. Valverde's side are unbeaten at home since losing to Real Madrid in August's La Liga opener and we are tipping them to come away with another victory in front of their home supporters.