The visitors are currently 15th in the table, nine points ahead of 18th-placed Cadiz with six matches left, while Villarreal sit in ninth spot, nine points behind sixth-placed Real Sociedad.
Match preview
Villarreal finished fifth in Spain's top flight last season and have only been lower than seventh on one occasion at the end of a La Liga campaign since gaining promotion back to this level in 2013.
The Yellow Submarine have found it difficult to show their best form this term, though, and they are currently ninth in the table, boasting a record of 11 wins, nine draws and 12 defeats from their 32 matches this season to collect 42 points.
Marcelino's side are nine points behind sixth-placed Real Sociedad in the race to qualify for the Europa League, but they are only six points behind seventh-placed Real Betis, so a spot in the Conference League playoff round for next season is certainly within reach.
Villarreal have only lost once in Spain's top flight since January 13, and they will enter this match off the back of a 2-1 victory over basement side Almeria last weekend.
The Yellow Submarine's home form this season has been disappointing, though, only picking up 19 points from their 16 fixtures in front of their own fans, suffering seven defeats in the process.
Rayo actually have the third-worst home record in La Liga this season, but they have been relatively solid on their travels, boasting a record of four wins, five draws and seven losses from 16 matches.
The capital outfit are in good form, winning two and drawing two of their last four league matches, including a 2-1 success over Osasuna last time out, with their recent run easing their relegation fears.
Inigo Perez's side are not yet safe, though, as they sit 15th in the table on 34 points, nine points clear of the relegation zone with six games left, so there is still a scenario which could see them pulled into trouble.
Rayo, who are in their third straight campaign at this level, will bring a three-game unbeaten run against Villarreal into this match, including a 1-0 success in the corresponding fixture between the two sides last season.
The points were shared in a 1-1 draw when they locked horns in Madrid last September, though, and Villarreal have won three of their last six meetings in Spain's top flight.
Villarreal La Liga form:
W
W
W
L
D
W
Villarreal form (all competitions):
W
W
W
L
D
W
Rayo Vallecano La Liga form:
D
L
W
D
D
W
Team News
Villarreal have doubts over four players leading into this match, with Yeremy Pino, Eric Bailly, Juan Foyth and Denis Suarez potentially all unavailable for selection.
However, the home side's squad will be boosted by the returns of Raul Albiol and Santi Comesana, who were not involved against Almeria last time out due to suspensions.
Albiol and Comesana should both return to the starting side on Saturday, but it is otherwise expected to be the side that took to the field for the first whistle against the team at the bottom of the division, with Gerard Moreno operating alongside Alexander Sorloth in the final third of the field.
As for Rayo, Diego Mendez and Alvaro Garcia will again definitely be absent due to muscular problems, while Kike Perez and Aridane Hernandez remain fitness doubts.
Head coach Perez is unlikely to find a reason to change a winning side this weekend, with a 4-4-2 formation again set to include Oscar Trejo alongside Sergio Camello in the final third.
Jorge de Frutos and Isi Palazon should continue in the wide areas for the capital outfit, with the likes of Raul de Tomas and Radamel Falcao set to be among the substitutes once again.
Villarreal possible starting lineup:
Jorgensen; Femenia, Albiol, Mosquera, Pedraza; Akhomach, Parejo, Comesana, Baena; G Moreno, Sorloth
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Mumin, Lejeune, Chavarria; De Frutos, Valentin, U Lopez, Palazon; Camello, Trejo
We say: Villarreal 2-1 Rayo Vallecano
Villarreal's recent form has been impressive, and the Yellow Submarine still have an outside chance of claiming a European spot this season. Rayo will be in a confident mood heading into the contest, and we are backing the visitors to score, but Villarreal should be able to navigate their way to an important three points.