The home side are currently ninth in the table, one point and one position behind Osasuna, who will enter the match off the back of a 2-1 victory over basement side Elche last weekend.
Match preview
Rayo were in the running for a possible European finish earlier this year, but an eight-game winless run in Spain's top flight has seen them drop down the table into ninth position.
Andoni Iraola's side were last victorious at home to Almeria at the start of February; since then, they have drawn five and lost three of their eight matches, including a 2-1 home defeat to Atletico Madrid last weekend.
Rayo are one point behind eighth-placed Osasuna and three from Athletic Bilbao in seventh, but they are now eight points behind sixth-placed Real Betis heading into the next set of fixtures in Spain's top flight.
Los Franjirrojos finished 12th on their return to the top flight last season, while they have not claimed a top-half finish since 2013, so it could be a successful campaign for the club despite their recent struggles for wins.
Rayo have actually lost each of their last three La Liga games against Osasuna, including a 2-1 defeat in the corresponding match earlier this season.
Osasuna, meanwhile, will enter the contest off the back of a 2-1 win over Elche, with on-loan Barcelona attacker Abde Ezzalzouli scoring a second-half brace to turn the match around.
Los Rojillos have picked up four points from their last two league games, which has left them in eighth position in the table, two points behind seventh-placed Athletic.
Osasuna will have their eyes on a possible top-seven finish, but they are also chasing success in the Copa del Rey, preparing to take on Real Madrid in the final of the competition at the start of May.
Jagoba Arrasate's side have the ninth-best away record in the division this season, but they have only managed three wins from 14 matches on their travels.
Rayo, meanwhile, have found it difficult to show consistency on their own patch, picking up 20 points from their 14 La Liga matches in front of their own supporters, which points to a close game on Friday night.
Rayo Vallecano La Liga form:
L
D
L
D
D
L
Osasuna La Liga form:
W
D
L
L
D
W
Osasuna form (all competitions):
D
L
L
D
D
W
Team News
Rayo currently have a fully-fit squad, but the home side will be without the services of Florian Lejeune following his red card against Atletico last time out.
Esteban Saveljich could come into the side as Lejeune's replacement, while Sergio Camello and Oscar Trejo are also pushing to be involved in the first XI after featuring off the bench against Diego Simeone's side.
Raul de Tomas and Unai Lopez are likely to be the two players to drop out of the side, but Alvaro Garcia and Isi Palazon should retain their spots in the side.
As for Osasuna, Ruben Garcia remains on the sidelines with a muscular issue, while Aridane Hernandez and Ezequiel Avila are major doubts for the contest.
Darko Brasanac had to be substituted in the first half of the clash with Elche last time out, and the midfielder is also unlikely to be available for selection here.
Jon Moncayola and Aimar Oroz could both come into the XI on Friday, but Ezzalzouli, Ante Budimir and Kike Barja should again feature as the front three against Rayo.
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Saveljich, Catena, F Garcia; Comesana, Valentin; Palazon, Trejo, A Garcia; Camello
Osasuna possible starting lineup:
Fernandez; Moncayola, U Garcia, D Garcia, Sanchez; Ibanez, Oroz, M Gomez; Barja, Budimir, Ezzalzouli
We say: Rayo Vallecano 1-1 Osasuna
There is not too much between these two teams in terms of quality, as the league table suggests, and we are expecting a close match on Friday night. Both managers would likely accept a point if it were offered ahead of kickoff, and we are predicting a low-scoring draw in this contest.