The French international missed both Thursday and Friday's training sessions due to a minor knock, and according to Sport, his availability for the clash remains uncertain. The precautionary absence would be a huge setback for Hansi Flick, who is already managing several injury concerns in defence.
With Kounde sidelined, teenager Xavi Espart was included in Friday's training session and could earn a place in the squad travelling to Madrid. The 18-year-old centre-back has impressed for Barcelona's youth teams this season and may now be called upon to provide cover.
However, there was some positive news for Flick as Frenkie de Jong returned to training after overcoming a brief illness that saw him sent home the previous day.
The Dutch midfielder was reportedly back in action on Friday morning and is now expected to be available for selection.
De Jong's return provides a vital boost for Barcelona's midfield ahead of what is expected to be a fiercely contested encounter at the Bernabeu.
Flick will be hoping his side can maintain their great start to the La Liga campaign, but Kounde's fitness remains a key concern with less than 48 hours to go before kick-off.
El Clasico between Real Madrid and Barcelona takes place on Sunday, with Real Madrid leading the La Liga table by two points ahead of second-placed Barcelona.
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