Los Che's hopes of a European finish have taken a hit due to their recent struggles, while Rayo sit down in 16th spot in the table and are not yet guaranteed a spot in the top flight for the 2024-25 campaign.
Match preview
Valencia remain in the hunt for a European finish in La Liga, with the team sitting eighth in the table, five points behind seventh-placed Real Betis, who are currently qualifying for the Conference League playoff round.
Los Che's recent form has harmed their chances of finishing in the top seven, though, losing each of their last three against Real Betis, Barcelona and Alaves.
Ruben Baraja's side have two tough matches after this one, facing Real Sociedad and Girona, before finishing their season away to Celta Vigo on May 25.
Valencia finished 16th in La Liga last season, which proved to be their worst top-flight campaign since being relegated in 1985-86, but there has been a clear improvement this term, and the signs are certainly positive for the future, with a young squad showing their credentials.
Los Che have been strong at home this season, picking up 29 points from their 17 fixtures at Mestalla, and they will be welcoming a Rayo outfit that have 17 points from their 17 away matches in 2023-24.
Rayo have actually only lost one of their last six league matches against Valencia, which proved to be a 1-0 defeat when the two teams locked horns for the reverse fixture earlier this season.
Three of their last five meetings at this level have finished all square, including a 1-1 at Mestalla last term, so the visitors will not enter Sunday's match with an inferiority complex.
Rayo have lost their last two in La Liga, going down 3-0 at Villarreal on April 28 before suffering a 1-0 home defeat to already-relegated Almeria last time out.
Inigo Perez's side sit 16th in the table, eight points clear of the relegation zone with four games left, so they are in a strong position when it comes to remaining in the top flight.
Rayo have finished 12th and 11th in their two La Liga campaigns since being promoted back to the top flight, and they looked on course for a top-half spot due to their form in the first half of the season, but they have been gradually sliding down the table in recent months.
Valencia La Liga form:
D
W
W
L
L
L
Rayo Vallecano La Liga form:
W
D
D
W
L
L
Team News
Valencia will welcome number one goalkeeper Giorgi Mamardashvili back into their squad this weekend, with the 23-year-old serving a suspension against Alaves.
Jaume Domenech, who had replaced Mamardashvili last time out, was actually injured in the first half of the contest, so he will be unavailable for selection this weekend.
Jesus Vazquez, Fran Perez and Mouctar Diakhaby are also absent through injury, while Jose Gaya is not ready to return to action despite being back in training earlier this week.
Sergi Canos is pushing to be included in an attacking position, but Andre Almeida is expected to keep his spot alongside Hugo Duro in the final third of the field.
As for Rayo, Diego Mendez remains on the sidelines due to a ligament issue, but the capital side are otherwise in strong shape ahead of this weekend's contest.
There will be a return to the squad for Pathe Ciss, who was suspended against Almeria last time out, and the midfielder is set to be brought back into the XI.
Head coach Perez is also expected to make a couple of attacking changes for Sunday's match, with Jorge de Frutos and Randy Nteka potentially coming into the starting side at Mestalla.
Valencia possible starting lineup:
Mamardashvili; Correia, Mosquera, Gasiorowski, Vazquez; Gonzalez, Pepelu, Guerra, Lopez; Duro, Almeida
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Mumin, Lejeune, Chavarria; Palazon, Valentin, Ciss, A Garcia; Nteka, De Frutos
We say: Valencia 1-0 Rayo Vallecano
Valencia need a win to boost their European hopes, and we are expecting them to triumph on Sunday against a Rayo side that have largely struggled in the second half of the season. However, it is likely to be a tight affair, with perhaps just one goal separating the two sides at the end of the 90 minutes.