WATCH: Nacho's controversial free-kick for Real Madrid v Sevilla

Real Madrid moved a step closer to the La Liga title with a 4-1 victory over Sevilla, but they were sent on their way to all three points by a controversial opener.

Mateo Kovacic was brought down on the edge of the Sevilla penalty area, handing Real a free-kick in a dangerous position.

But before Sevilla could even put a wall together, Nacho stroked the ball into the net and referee Alberto Undiano allowed the goal to stand, sparking wild protests from the visitors.

The goal sent Real on their way to a 4-1 victory which saw Cristiano Ronaldo score his 400th goal in all competitions for the club. He quickly added goal 401 as Real rounded off a comprehensive victory at the Bernabeu.

The win sees Zinedine Zidane's side remain second in La Liga level on points with Barcelona, who beat Las Palmas 4-1, but with a game in hand against Celta Vigo on Wednesday, live on Sky Sports.

Watch Real Madrid's controversial opener in the 4-1 win against Sevilla by hitting play on the video at the top of the page.