Real Madrid ended 2018 by winning a third consecutive FIFA Club World Cup in the UAE but they've been brought back down to Earth in the new year.

A brace by former Arsenal maestro Santi Cazorla held them to a 2-2 draw at Villarreal at Thursday and left them fifth in La Liga, seven points behind leaders Barcelona.

The reigning Champions League holders welcomed mid-table Real Sociedad to the Bernabeu on Sunday but their domestic struggles continued as they lost 2-0.

Marcelo was whistled by the crowd for his involvement in the move that led to Casemiro conceding a penalty, which Willian Jose converted to give the visitors a third-minute lead.

The match was particularly special for Vinicius Junior because it was his very first league start for Madrid, and their fans reacted the same way to his performance.

Vinicius finally gets La Liga start for Madrid

Vinicius was officially presented as a Real player back in July after leaving Flamengo, where he'd been since 2005, for a reported fee of €46 million.

The talented Brazilian boasts four goals in five Real Madrid Castilla games this season and he's also featured 12 times for the under-pressure senior team.

Real manager Santiago Solari named Vinicius in his starting XI against Sociedad on the left of a front three alongside Lucas Vazquez and Karim Benzema.

Los Blancos dominated possession but had trouble creating clear-cut scoring opportunities, however Vinicius Jr really caught the eye.

The exciting winger was direct in his dribbles, full of energy and constantly trying to use his speed to get in behind and stretch Sociedad's defence.

Vinicius' driving 65th-minute run and subsequent collision with goalkeeper Geromino Rulli could, and probably should, have been given as a penalty by the referee.

Real Madrid fans react to Vinicius' display

On what was his first league start for the club, Madrid fans on Twitter were in agreement that the 18-year-old was their best player, biggest threat and only hope of scoring.

One supporter labelled him the teenager as the 'only world-class player' on the pitch for Madrid, while another said he was the only one trying to making something happen.

Check out the best tweets below:

With Cristiano Ronaldo now at Juventus and Gareth Bale injured yet again, the fact an 18-year-old is Real Madrid's most potent attacker really sums up their current situation.

Solari's men simply need wins in upcoming league games with Real Betis, Sevilla and Espanyol because they're not even in the Champions League qualification places as things stand.

What are YOUR thoughts on Vinicius' display against Sociedad? What do YOU think needs to change at Real Madrid? Leave YOUR opinions in the comments box below!