Liverpool have lodged a complaint with Real Madrid and UEFA after being allocated just 1,800 tickets for their Champions League clash with the Spaniards at the Bernabeu in March.
The stadium can officially hold over 81,000 supporters, but that number has been scaled back because of ongoing construction work.
Last season, Real Madrid capped their level of attendance to 50,000, but this season entertained over 63,000 fans when bitter rivals Barcelona visited the Spanish capital.
Liverpool have said 1,800 is "significantly less than expected", as reported by The Athletic.
UEFA's regulations mean the Reds are entitled to five per cent of the stadium's available capacity, which would put the correct figure around 3,000.
Real Madrid and UEFA are yet to issue a response.
