The hosts are hoping to keep their fading European hopes alive, while Villarreal head into the final two games five points adrift of the Champions League places.
Match preview
Rayo's unlikely European pursuit has lost momentum in recent weeks, with their last five matches yielding four defeats and just one victory over Real Valladolid.
Since beating Valladolid earlier this month, Rayo have fallen to three consecutive defeats, including a 2-1 loss to Real Madrid on Wednesday.
Los Franjirrojos would have been proud of their efforts at the Santiago Bernabeu after Raul de Tomas struck in the 84th minute to cancel out Karim Benzema's first-half opener, but a late Rodrygo winner ensured the visitors returned to Vallecas empty-handed.
Since the midweek defeat, reports have emerged that Iraola has decided against signing a new contract, and will leave the club at the end of the season amid speculation that his next job could be in England.
With four points separating 12th-placed Rayo from the top seven, European qualification still remains a possibility, and Iraola will be urging his side to remain focused on Sunday's contest rather than his own future, as they look to complete the double over Villarreal for the first time in La Liga after they claimed a narrow 1-0 win in the reverse fixture.
Villarreal have already guaranteed to finish no lower than fifth position, but the Yellow Submarine still have an outside chance of qualifying for the Champions League after dropping just two points in their last six matches.
Quique Setien's side made light work of their midweek home meeting with Cadiz, as Nicolas Jackson netted a brace for a third consecutive home game to guide his side to a 2-0 victory.
The Yellow Submarine hold the head-to-head advantage over fourth-placed Real Sociedad, who are five points better off and require just two points to secure a Champions League qualification.
However, should the Basque side fail to keep up their end of the bargain, Villarreal will need to claim maximum points in their final two fixtures against Rayo and Atletico Madrid to sneak into the top four.
Only three teams have scored more league goals this season than Villarreal, who have racked up 56 goals in 36 games, and that firepower could be decisive on Sunday.
Rayo Vallecano La Liga form:
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L
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Villarreal La Liga form:
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Team News
After serving a two-match suspension, Mario Suarez is set to return to the matchday squad, but he will have to settle for a place on the bench.
Oscar Trejo dropped out of the starting lineup for the midweek defeat to Real Madrid, but he could come back into the side on Sunday.
Having scored three goals in Rayo's last four games, De Tomas is expected to be given the responsibility of leading the line.
As for the visitors, Francis Coquelin is a long-term absentee, while there are doubts over the availability of Raul Albiol and Jose Luis Morales.
Due to the busy schedule, Setien rotated his side for the midweek win over Cadiz, and the Villarreal boss could recall Juan Foyth, Alfonso Pedraza, Etienne Capoue, Alex Baena and Samuel Chukwueze to the starting lineup.
Jackson has racked up eight goals in his last six appearances, and the Senegal international will have the chance to add continue his impressive form when he starts up front on Sunday.
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Lejeune, Catena, F. Garcia; Comesana, Valentin; Palazon, Trejo, A. Garcia; De Tomas
Villarreal possible starting lineup:
Reina; Foyth, Mandi, Torres, Pedraza; Parejo, Capoue; Chukwueze, Baena, Pino; Jackson