The visitors are currently fifth in the La Liga table, only two points behind fourth-placed Villarreal, while Rayo have dropped into 13th, with the capital outfit losing three of their last four games in Spain's top flight.
Match preview
Rayo have a record of four wins, four draws and five defeats from their 13 La Liga matches this season, with a total of 16 points leaving them in 13th spot in the table, six points above the relegation zone.
The capital outfit are on a disappointing run of form in the league, losing three of their last four, including their last two against Las Palmas and Sevilla, failing to triumph in La Liga since a home game with Alaves on October 26.
Inigo Perez's side are active in the Copa del Rey, having beaten Villamuriel in their 2024-25 opener at the end of October, and their journey in that competition will continue away to Unionistas de Salamanca next week.
Rayo will be determined to end 2024 on a positive note in La Liga, though, as they bid to improve on what was a disappointing 2023-24 campaign, with the team finishing down in 17th spot in the table.
The Madrid club have picked up eight points from their six home league matches this term, while Athletic have collected eight points from their six La Liga fixtures away from San Mames in 2024-25.
Athletic will enter Sunday's clash off the back of a 3-0 win over Elfsborg in the Europa League, with the result leaving them second in the overall table, picking up 13 points from their five matches in the competition this term.
The Lions were also 1-0 winners over Real Sociedad in the Basque derby last weekend, with Oihan Sancet netting the only goal of the contest in the 26th minute, and Ernesto Valverde's side are unbeaten in all competitions since the start of October.
A record of six wins, five draws and three defeats in La Liga this season has brought them 23 points, which is enough for fifth spot in the table, only two points behind fourth-placed Villarreal.
Athletic will be expecting to challenge the likes of Villarreal and Girona for a top-four spot this term, while they are also seemingly serious contenders to triumph in the Europa League.
The Lions are unbeaten against Rayo in Spain's top flight since September 2021, while they won both league matches between the two sides in 2023-24, including a 1-0 success in the corresponding fixture in Madrid.
Rayo Vallecano La Liga form:
D
W
L
W
L
L
Rayo Vallecano form (all competitions):
W
L
W
W
L
L
Athletic Bilbao La Liga form:
L
W
D
D
D
W
Athletic Bilbao form (all competitions):
D
D
W
D
W
W
Team News
Rayo will be missing Unai Lopez through suspension on Sunday, with the midfielder picking up a milestone booking in his side's 1-0 defeat to Sevilla at Estadio Ramon last weekend.
As a result, there is likely to be a spot in the side for Pathe Ciss, but head coach Perez is expected to resist the temptation to shuffle his pack despite the disappointment of the result last time out.
One further change could come in the final third of the field, though, with Sergio Camello potentially replacing Randy Nteka.
As for Athletic, Benat Prados will sit this game out through suspension, with the midfielder picking up a milestone yellow card in the narrow success over Real Sociedad last weekend.
As a result, there could be a spot in midfield for Mikel Jauregizar, while Alvaro Djalo, Oscar de Marcos and Yeray Alvarez should also return after starting on the bench in the Europa League last time out.
Djalo is likely to be given the nod over Gorka Guruzeta in the final third of the field, with Nico Williams, Sancet and Inaki Williams also again set to feature in the attacking positions for the Lions.
Rayo Vallecano possible starting lineup:
Batalla; Ratiu, Lejeune, Mumin, Chavarria; Gumbau, Valentin, Ciss; De Frutos, Camello, A Garcia
Athletic Bilbao possible starting lineup:
Simon; De Marcos, Vivian, Yeray, Yuri; Ruiz de Galarreta, Jauregizar; I Williams, Sancet, N Williams; Djalo
We say: Rayo Vallecano 1-2 Athletic Bilbao
Rayo are better than what they have shown in recent weeks, and the hosts will certainly be the fresher of the two sides heading into Sunday's contest. Athletic are in strong form at the moment, though, and we are expecting the Lions to navigate their way to what would be an important victory at this stage of the campaign.