El Clasico will determine who win the league between these two teams. If Madrid wins, they have given themselves more hope to win the league. if Barcelona wins, automatically they have won the title. However, if it ends in a draw, Barcelona still maintains their stand. It will be very annoying if Barcelona allow Madrid to defend the title this season, because they have the chance of winning the league currently.
With the composition of points like now, El Clasico will be a determinant of who will win the league and this assumption will go well if both teams continue to get points before El Clasisan takes place. A draw will provide a far greater opportunity for Barcelona to win the title and that is an advantage for them. It's hard to determine the title this season because both of them still have the same opportunity even though currently Barcelona is still three points ahead of Real Madrid.
This will be an important match for both teams, in addition to talking about rivalry, the determination of the title can also be seen how the results of the match. Barcelona is enough to benefit from playing in their own home so they will be motivated enough to beat Real Madrid.