Brazil international Vinicius, on as a substitute, scored but his goal was disallowed and then he was dismissed after a VAR review showed he pulled the hair of Villarreal's Nathan Saliba.
Real Madrid edge Villarreal, Vinicius sent off for hair pull
Yan Diomande earned Real Madrid a tight 1-0 victory over Villarreal on Saturday to keep them six points behind La Liga leaders Barcelona, even though winger Vinicius Junior was sent off for hair-pulling.
Jose Mourinho's Madrid battled through the final stages with 10 men but held on to their slender lead earned by 19-year-old winger Diomande to go provisionally third.
Champions Barca lead La Liga after a 3-0 win over Getafe, while Atletico Madrid are five points behind in second after they edged Alaves 2-1.
Despite Madrid's victory, Vinicius's red card left a bitter taste for Los Blancos, with the winger running the risk of a potential ban which could keep him out of the Clasico on October 25.
"I don't know what's going on with the referees, with this red card, I don't understand, but the most important thing is the victory," said Madrid midfielder Aurelien Tchouameni.
Madrid coach Mourinho complained bitterly about refereeing decisions which did not go his team's way in the derby defeat by Atletico before the recent international break.
Striker Kylian Mbappe was fit to start the match for Madrid at their Santiago Bernabeu stadium after suffering a knee problem playing for France during the international break.
There were a smattering of whistles for the superstar forward, with some fans believing he has been unprofessional in recent weeks, but also applause from other supporters.
Mbappe, a candidate for the Ballon d'Or trophy later this month, was Madrid's most threatening player in the first half, although he had little competition.
Mourinho started with out-of-form winger Vinicius on the bench, following his trips to Australia and India with Brazil during the international break.
Madrid improved defensively, giving Villarreal few chances of note, but struggled to build much in attack themselves in a drab opening half.
- Mbappe frustrated -
Mbappe struck the post from Alvaro Carreras's lay-off as Madrid pushed Villarreal back early on.
Villarreal soon gained a foothold and restricted Madrid's opportunities, until Mbappe forced a good save from Peter Gulacsi.
There was some more mild whistling for Madrid's display from their fans at half-time, but soon they were able to celebrate summer arrival Diomande's first goal for the club.
The Ivorian winger, Madrid's record 140-million-euro ($157 million) signing, produced a sharp low finish into the far corner after good work from Federico Valverde to play him in.
Vinicius thought he had doubled Madrid's lead after Jude Bellingham charged in down the left and cut the ball back for him.
However the winger's joy turned to anger after referee Isidro Diaz de Mera was called to watch Vinicius's hair pull on Saliba in the build-up by VAR and sent off the Brazilian, voiding his goal.
Madrid's Belgian goalkeeper Thibaut Courtois, who had made a couple of smart saves earlier in the half, produced an acrobatic stop to thwart Carlos Romero.
Mbappe was denied again by Hungarian goalkeeper Gulasci as the forward left the Bernabeu frustrated in his hunt for goals, although his team were able to clinch three important points to stay on Barca's trail.
