While Madrid do not have an awful lot to play for at this stage of the campaign, the same cannot be said for Rayo, who are in desperate need of a win to give themselves a chance of escaping the bottom three.
There is no getting away from the fact that it has been a tough campaign for Rayo. Indeed, a record of seven wins, seven draws and 20 defeats has left them bottom of the table on 28 points. The capital side are seven points off 17th-placed Real Valladolid and face a tough task to remain in the top flight.
Rayo spent five straight seasons in La Liga between 2011 and 2016 before dropping into the Segunda Division. They finished a disappointing 12th in the second tier at the end of the 2016-17 season, but secured a return to La Liga by winning the league last term.
It does appear that Los Franjirrojos will be returning to the second tier, however, as they have struggled to compete this term. Indeed, not only do Rayo have the worst defensive record in La Liga this season, they have only managed to hit the back of the opposition's net on 36 occasions.
No team has lost more games than Rayo in Spain's top flight this season, while only Huesca (6) have won fewer matches. Paco Jemez's side were thumped 5-0 at Sevilla on Thursday night and now face four matches against Madrid, Levante, Valladolid and Celta Vigo.
The fact that Los Blancos have little to play for should work in the home side's favour this weekend, and they will actually bring a three-game unbeaten home run into the contest.
Indeed, Rayo have drawn with Real Betis and Huesca, in addition to beating Valencia, in their last three matches in front of their own supporters, which will hand them confidence ahead of this match.
The home side's task will be significantly more difficult this weekend, though, due to the fact that they will be without the services of Raul De Tomas, who is on loan from Madrid and therefore ineligible. The forward has netted 14 times in La Liga this term and it is difficult to know where the goals will come from without the 24-year-old.
Recent form: DLWLDL
Madrid's goalless draw at Getafe on Thursday night left them six points off second-placed Atletico Madrid in the table. There is no danger of Los Blancos finishing lower than third, but it does appear that they will have to settle for that position, rather than the spot immediately behind Barcelona.
Barca will be looking to win the title this weekend and currently sit a huge 15 points ahead of Madrid, who have been unable to compete for the championship during the 2018-19 campaign.
Los Blancos have won 20 of their 34 matches this season but have also lost nine times, which is not good enough for a team of their ilk. Zinedine Zidane is back at the club, though, and it appears likely that the European champions will spend some serious money in this summer's transfer window.
Investment is certainly needed if Madrid are to be a force next season - Eden Hazard is likely to arrive from Chelsea, while it has been suggested that Borussia Dortmund's Jadon Sancho is a transfer target.
Having fallen at the last-16 stage of the Champions League and semi-finals of the Copa del Rey, Madrid only have the league to focus on - they will host Villarreal after the clash with Rayo, before travelling to Real Sociedad and welcoming Betis in their final two matches of the 2018-19 campaign.
Madrid's form has actually not been too bad in recent weeks, having drawn two and won two of their last four in the league. Getafe probably should have won Thursday's match, though, and Zidane has some big problems to address if the team are to be a force next season.
The future of Gareth Bale is certainly of paramount importance - Madrid are said to be keen to sell, but the Welshman could decide to sit on his massive wages at the club. Bale again struggled against Getafe and it seems extremely unlikely he will be handed another starting role on Sunday night.
The visitors will be the huge favourites to triumph against Rayo, though, considering that they have won the last 11 league matches between the two teams, including a 3-2 success on their last visit to their capital rivals in April 2016.
Recent form: WLWDWD
Recent form (all competitions): WLWDWD
Rayo had reportedly been attempting to gain clearance for De Tomas to play this weekend, but it does appear that the centre-forward will be ineligible, which is a huge blow.
Gorka Elustondo is still on the sidelines with a knee injury, but head coach Jemez has no fresh injury concerns from the team that started against Sevilla last time out.
As for Madrid, Zidane is likely to shuffle his pack once again. Sergio Ramos and Alvaro Odriozola are both still injured, but Vinicius Junior is in the latter stages of his recovery from a leg injury and could make the squad.
There could also be a first appearance under Zidane for Thibaut Courtois, who made the bench against El Geta.
Rayo Vallecano possible starting lineup:
Garcia; Velazquez, Galvez, Amat; Embarba, Agbo, Kakuta, Suarez, Moreno; Di Santo, Guerra
Real Madrid possible starting lineup:
Courtois; Carvajal, Nacho, Varane, Marcelo; Modric, Kroos, Casemiro; Asensio, Benzema, Lucas
Head To Head
As mentioned, Madrid have won each of the last 11 top-flight meetings between the two teams.
Earlier this season, Los Blancos recorded a 1-0 victory at the Bernabeu, while they ran out 3-2 winners when they last travelled to Rayo in La Liga back in April 2016.
Madrid also beat Rayo 10-2 in Spain's top flight during the 2015-16 campaign.
We say: Rayo Vallecano 1-3 Real Madrid
Rayo will be fired up to collect all three points, but they are poor defensively and Madrid still have excellent players despite their struggles this season. We fancy the visitors to collect all three points with a 3-1 win.