Hummel is suing Rangers for £9.5m in lost kit sales as a judge has ordered the club to release sales figures.
Elite Sportswear, the company behind the former kit manufacturers to the Ibrox club, lodged court papers and the Danish firm launched proceedings at the Court of Session in Edinburgh this week.
It is understood that the figures in question relate to club store on Glasgow’s Argyle Street, as well as in Belfast and online.
The court was told that within six weeks of entering into a contractual agreement in September 2018 Rangers were found to be “not performing” as per the agreement.
Elite Sportswear's KC, David Thompson, told presiding judge Lord Braid that they are still none the wiser as to what the exact sales figures for the period are. He therefore ruled that the Ibrox club must now disclose the numbers requested.
Lord Braid said: “In September 2018 the parties entered into a contract for Elite Sports to supply Hummel kits and replica kits and had worldwide rights to distribute Rangers related products.
“The decision in London by Mr Justice Teare in October 2018 resulted in the business not performing its obligations as part of the contract - it is clear to me that Rangers entered into this contract and have failed to perform.
“We are seeking loss of profit suffered by the pursuer for season 2018/19, 20/21 and up to and including September 2023 - at this stage the exact sales figures of shirts sold are still unknown and all we have is an estimate.”
In June, JD Sports and Elite Sports confessed to "cartel activity" in illegally fixing the retail prices of Rangers-branded replica kits and other clothing.
The Competition and Markets Authority (CMA) said the price fixing took place from September 2018 until at least July 2019.
The football club also took part in the alleged collusion, but "only to the extent" of fixing the retail price of adult home short-sleeved replica shirts from September 2018 to at least mid-November 2018.
The CMA stated that all three parties allegedly colluded to stop JD Sports undercutting the retail price of the shirt on Elite’s Gers Online store.
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