World superstars Lionel Messi and Cristiano Ronaldo will once again be centre stage on Wednesday when El Clasico foes Barcelona and Real Madrid meet in the Copa del Rey.
All eyes will be on the pair as the debate continues regarding the best player in the world and their competition was in full evidence at the weekend.
Ronaldo scored a hat-trick in Real's 4-0 win over Getafe on Sunday but Messi, who once again beat the Portugal captain to the 2012 Ballon d'Or, then netted four against Osasuna.
But the rivalry between the two clubs also surpasses any individual battle and Barcelona will therefore visit Madrid in the hope of adding to the problems at Real.
Copa del Rey holders Barcelona are 11 points clear at the top of La Liga, with third-placed Real 15 points behind after a stormy and troubled campaign.
Jose Mourinho's future is increasingly gloomy after reports of in-house fighting and spats with Spanish media, which have only led to increased speculation he will leave.
Tito Vilanova, who has had previous touchline confrontations with Mourinho, will consequently be keen to rub salt in wounds by gaining a first-leg advantage.
Real will be without defender Pepe and goalkeeper Iker Casillas due to injury while Angel Di Maria, Fabio Coentrao and Sergio Ramos are all suspended.
Barcelona can welcome back Gerard Pique from a ban and Jordi Alba, Andres Iniesta and Cesc Fabregas are expected to start after being rested against Osasuna.
The 22-year-old was a key member of the South Korean Olympic squad that took bronze at London 2012, before then going on to make his full international debut in October.
Yun has been linked to a number of clubs in recent times, including west London rivals Fulham, but has joined QPR on for an undisclosed fee from K-League side Chunnam Dragons.
The left-back has been granted a work permit and will be eligible to play for the Rs once he obtains a visa.
Yun joins fellow January acquisitions Loic Remy and Tal Ben Haim at Loftus Road, where he links up with countryman Park Ji-sung.
The defender may be the first of several signings before the transfer deadline on Thursday, with Peter Crouch, Christopher Samba and Etienne Capoue amongst those on QPR's radar.
