Ernesto Valverde's side are currently sixth in the table, boasting 10 points from their opening five matches, while Rayo are ninth, having picked up seven points during a solid start to the season.
Match preview
Athletic finished eighth in Spain's top flight last season, but they were fourth in 2013-14 and fifth in 2015-16, and a European challenge this term cannot be ruled out, as there have been positive signs early in the season.
The Lions have won three, drawn one and lost one of their five matches to collect 10 points, which has left them in sixth position in the table, while they have only conceded twice in Spain's top flight this term.
Valverde's side started their campaign with a goalless draw at home to Mallorca before winning their next two against Valencia and Cadiz, scoring five times in the process and keeping two clean sheets.
Athletic then lost 1-0 at home to Espanyol on September 4 but managed to return to winning ways away to Elche last time out, recording a 4-1 victory, with Oihan Sancet, Nico Williams and Alex Berenguer on the scoresheet at Estadio Manuel Martinez Valero.
The Basque outfit have won five of their last seven La Liga matches with Rayo, but they suffered a 2-1 defeat to the capital outfit in the corresponding game between the two sides last term.
Rayo were 12th in La Liga last season on their return to the top flight, and they will be pleased with their start to this campaign, picking up a respectable seven points from five matches to occupy ninth spot in the table.
Los Franjirrojos started their season with a goalless draw at Barcelona before recording a 2-0 victory over Espanyol one week later to move onto four points from their opening two games.
Rayo then lost back-to-back games against Mallorca and Osasuna but managed to return to winning ways last time out, beating Valencia 2-1 at home, with Isi Palazon's early effort and an own goal from Nico Gonzalez helping the capital outfit overcome Gennaro Gattuso's team.
As mentioned, Los Vallecanos have struggled to secure wins in recent games with Athletic, but their 2-1 victory at San Mames last term should give them confidence heading into this match.
Andoni Iraola's side would view 10 points from six matches as a strong start to the campaign, but they will be taking on an Athletic outfit that have been victorious in three of their last four matches.
Athletic Bilbao La Liga form:
Rayo Vallecano La Liga form:
Team News
Athletic will again be without the services of Ander Herrera, Yuri Berchiche and Mikel Balenziaga for this match, while Mikel Vesga is also a doubt for the home side.
There are no concerns in terms of the starting XI from the clash with Elche, though, so it would not be a surprise to see the same group of players take to the field for the first whistle.
Nico Williams and Berenguer were both on the scoresheet last time out and should again support Inaki Williams at centre-forward, while Sancet should retain his midfield spot alongside Dani Garcia.
As for Rayo, Salvi Sanchez, Diego Lopez and Andres Martin were all missing against Valencia, and the trio are again likely to be unavailable for this weekend's contest.
Head coach Iraola has plenty of options for change, particularly in the final third of the field, with Radamel Falcao and Randy Nteka pushing for starting roles against Athletic.
However, Alvaro Garcia, Oscar Trejo and Palazon are again likely to support Sergio Camello in the final third of the field, while Santi Comesana should retain his position in the middle of the park.
Athletic Bilbao possible starting lineup:
Simon; De Marcos, Vivian, I Martinez, Lekue; Sancet, D Garcia; N Williams, Muniain, Berenguer; I Williams
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Lejeune, Catena, F Garcia; Comesana, Valentin; Palazon, Trejo, A Garcia; Camello
We say: Athletic Bilbao 2-1 Rayo Vallecano
Rayo deserve credit for their start to the season, and they have already put in strong away performances at Barcelona and Espanyol this term. Athletic are generally strong in front of their own fans, though, and we are expecting the Basque outfit to put another three points on the board here.