A late goal from Karim Benzema sealed a 1-0 win for Real Madrid at Rio Vallecano on Saturday and allowed the LaLiga leaders to extend their advantage at the top of the standings.
They are now nine points ahead of second-placed Sevilla, who will play third-placed Real Betis on Sunday.
Real Madrid looked slow and disjointed at Valleques and held on to an almost goalless draw until Benzema and Vinicius Jr. worked their magic seven minutes out of time.
The France striker found Vinicius with a brilliant pass and ran into space to retrieve the ball and finished from close range with a touch.
LaLiga's top scorers Benzema and Vinicius have now scored 32 of the team's 52 goals this season.
After the match, Real manager Carlo Ancelotti said: "I am very satisfied with the effort, the commitment, the intensity of the team. We won. It was difficult with the atmosphere, the opponent, the pitch, it was complicated so I think we did well. Performed, many teams here haven't won. It was a game that had to be like that, and we delivered."
Real goalkeeper Thibaut Courtois made two brilliant saves in the second half, keeping out a bullet header from Mario Suarez and a close shot from Alvaro GarcÃa.
"It was a complicated game because most of the ground was in very bad shape," Courtois told reporters.
"I don't think it's good for LaLiga's image to play in a field like this. It's far from ideal. It's good for us that Benzema and Vinicius are in form. After four years together they have a level of connection." reached which is unbelievable."
The Rayo players were also not happy when referee Isidro Diaz de Mera failed to send midfielder Casemiro in despite a stud-up challenge on Oscar Valentin. The incident was reviewed but VAR allowed the yellow card shown by the referee to stand.
Ancelotti was also asked about his midfield trio for Madrid's Champions League second leg against Paris Saint-Germain on 9 March and indicated that Luka Modric, Toni Kroos and Federico Valverde could be picked there.
"It could be yes, it's the midfield that has the most potential to play that game," said Ancelotti, whose team trail PSG 1-0 on aggregate after round 16 of the first leg. Is. "I have to say Valverde came and played well, Rodrigo also, he gave energy to the team at a crucial moment in the game."