The newly-promoted outfit currently occupy 10th spot in the La Liga table with seven points from their opening five games, while Tuesday's hosts sit two points better off in fifth place.
After a somewhat underwhelming 10th-placed finish last season, Athletic Bilbao have enjoyed a relatively strong start to the new campaign.
After back-to-back draws to start, Marcelino's men put their first three-point haul on the board with a 1-0 away victory over Celta Vigo.
The Basque outfit then made it consecutive victories, as Dani Vivian and Inaki Williams fired them to a 2-0 home win over Mallorca, before earning a commendable point against Atletico Madrid last time out.
Athletic Club held the defending champions to a goalless draw to extend their unbeaten run, and Marcelino's side will now look to return to winning ways and continue their strong start in style.
That will be no easy task though, as they meet a Rayo Vallecano side full of optimism after an impressive start of their own.
Following their promotion from the second tier last term, Andoni Iraola's side had a tough start to the campaign, losing consecutive games to Sevilla and Real Sociedad.
Having come up with the ultimate objective of cementing themselves as a top-flight outfit, Iraola's men will look to continue building momentum to ensure they avoid being dragged into a battle at the bottom end of the table.
After an impressive clean sheet against Atletico Madrid, Marcelino should not change his back line, with Inigo Martinez and Dani Vivian continuing to partner up at the heart of the defence.
Rayo Vallecano's only injury issue should be Martin Merquelanz, and Iraola will only make limited changes after their impressive victory last time out.
One change could be the introduction of star signing Radamel Falcao, who scored off the bench and is yet to start for his new side.
Athletic Bilbao possible starting lineup:
Simon; Lekue, Vivian, Martinez, Balenziaga; Berenguer, Vencedor, Garcia, Muniain; Williams, Garcia
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Saveljich, Catena, D Garcia; Comesana, Ciss; Palazon, Trejo, Bebe; Falcao
We say: Athletic Bilbao 2-1 Rayo Vallecano
While both sides come in with confidence, the hosts boast the stronger squad and should have enough to get over the line.
Marcelino's men boast quality all over the pitch and will look to continue their unbeaten start with a win on home turf.