The hosts held Sevilla to a draw last time out but remain two points adrift of safety in 18th spot.
Mallorca made a commendable start to life back in La Liga this season following their promotion, but a dismal run of form after the turn of the year quickly dragged them into danger.
Back-to-back wins in February will have provided cause for optimism, but Javier Aguirre's side went on to lose their next seven matches to drop into the relegation zone.
Following crucial wins over Alaves and Atletico Madrid, either side of a 3-0 defeat to Elche, Los Piratas again suffered consecutive losses heading into a tough clash with high-flying Sevilla last time out, but they were able to grind out a goalless draw in impressive fashion and add an important point to their tally.
While Aguirre will be pleased with that result, a victory for Cadiz in midweek meant that Mallorca remain two points adrift, and, with just two games left to play, they will know they realistically need at least one victory to stand a chance of preserving their top-flight status for another season.
They welcome a Rayo Vallecano side who enjoyed an even stronger start to the campaign following the two teams' promotions last term, as the visitors consistently remained in and around the top eight for the first half of the season.
Los Vallecanos also experienced a major dip in form after the halfway stage though, and, despite their head start, they briefly dropped worryingly close to the fight for survival following a 13-game winless run from the beginning of January to mid-April.
They were finally able to put an end to that slump with a 1-0 win over Espanyol, before beating Barcelona by the same scoreline against the odds at the Camp Nou to ensure they would not be dragged any further into the relegation scrap in the final straight of the season.
After those wins were followed by consecutive draws, Andoni Iraola's side hosted Villarreal last time out, and they were on the wrong end of a 5-1 thrashing, despite Sergi Guardiola initially drawing them level on the half-hour mark, as the visitors ran riot late in the first half.
Nonetheless, with the aim of survival comfortably achieved, Rayo Vallecano can focus on putting that result behind them and finishing the season on a high, with the chance to improve on their current position in 12th place and push for a top-half finish.
Following their impressive showing away at Sevilla, Aguirre is unlikely to make many alterations to his Mallorca side for Sunday's game, with the trio of Martin Valjent, Brian Olivan and Antonio Raillo bound to remain unchanged at the heart of the defence.
Vedat Muriqi will continue to lead the line, having scored four goals in 14 La Liga appearances since arriving on loan from Lazio in January.
Sergi Guardiola kept his place up front for Rayo Vallecano last time out, despite Radamel Falcao recently returning to the goals, and, after getting on the scoresheet, he should again be given the nod with the Colombian veteran likely used as an option off the bench.
Whichever striker is deployed will be supported by wingers Bebe and Alvaro Garcia, although they will be without creative midfielder Santi Comesana, who is suspended after being shown a 10th league yellow card of the season in the defeat to Villarreal.
Mallorca possible starting lineup:
Reina; Maffeo, Valjent, Raillo, Olivan, Costa; Battaglia, Sanchez, Sevilla; Muriqi, Rodriguez
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Maras, Catena, F Garcia; Lopez, Valentin; Bebe, Trejo, A Garcia; Guardiola
We say: Mallorca 2-1 Rayo Vallecano
With a tough trip to Osasuna looming on the final day, Mallorca should see Sunday's game as an absolute must-win, and we fancy them to outfight a Rayo Vallecano team who have less to play for in comparison and will be wounded from a thrashing last time out.
For additional data used by our team to analyse our suggesed result please click here.