Madrid - Real Madrid can take a huge step towards a first La Liga title in five years when they host Barcelona in El Clasico on Sunday.
Madrid lead Barca by three points at the top and have a game in hand on their rivals.
We look at five other Clasicos which have decided the title in recent years.
Barcelona 2 Real Madrid 1, 22 March 2015
Luis Suarez scored what he then described as his "most important goal" to tilt the title race decisively in Barca's favour as they went onto complete a treble of league, Champions League and Copa del Rey.
Cristiano Ronaldo cancelled out Jeremy Mathieu's early opener.
However, Suarez's brilliant control and finish early in the second-half handed Barca a four-point lead which they never surrendered in the final 10 games of the season despite Madrid dropping just two more points.
Barcelona 1 Real Madrid 2 2012, 21 April 2012
Ronaldo scored the goal that brought down the curtain on Barca's most successful ever era in Pep Guardiola's final Clasico in charge.
Madrid travelled to the Camp Nou with a healthy four-point lead and landed the knockout blow when Ronaldo rounded Victor Valdes before slotting home from a narrow angle.
Real Madrid 0 Barcelona 2, 10 April 2010
In one of the most hotly contested races ever, Barca won the title in Guardiola's second season by three points despite Madrid claiming a then club record 96 points.
The difference between the sides came at the Bernabeu as Xavi teed up Lionel Messi and Pedro Rodriguez either side of half-time.
Real Madrid 2 Barcelona 6, May 2 2009
Fondly remembered in Catalonia as one of the best Clasico performances of all time.
Largely forgotten, though, is that Madrid had threatened to snatch the title away by winning 17 and drawing one of their previous 18 games.
By doing so they had whittled Barca's lead at the top down from 12 to four points.
Madrid even took the lead through Gonzalo Higuain, but doubles from Messi and Thierry Henry plus goals from centre-backs Carles Puyol and Gerard Pique completed a famous Barca victory.
Barcelona 3 Real Madrid 3, March 10 2007
The night when Messi truly announced his arrival to the world, but which ultimately handed Madrid the title.
Messi scored all three of Barca's goals, the first of his now record 21 in Clasicos.
However, all three Messi strikes were equalisers after Ruud van Nistelrooy twice and then Sergio Ramos had put Madrid in front.
Real ended up winning the title thanks to their better head-to-head record against Barca having won 2-0 at the Bernabeu earlier in the season with both sides locked on 76 points.