An employment agency that provides staff for Sports Direct's largest warehouse is facing administration.
Transline Group said it was suffering from "tighter margins in the recruitment industry".
A spokesman said it was appointing administrators to protect its "business, employees and customers".
Last year, a Commons committee raised concerns over working conditions at Sports Direct's main Shirebrook warehouse.
The move gives the firm 10 days to find a solution to its financial problems.
MPs criticised the agency after it gave evidence at a Commons committee inquiry in 2016, saying their testimony "lacked credibility".
A Transline spokesperson said: "We are close to securing inward investment that will allow us to drive forward with continued growth and infrastructure development.
"We expect to hear more regarding potential trading investments imminently."
Unite assistant general secretary Steve Turner said the "current uncertainty" over Transline's future was "yet more evidence of the need for Sports Direct to wean itself off its over-reliance on temporary agency workers at its Shirebrook warehouse.
"Sports Direct must urgently move to put agency workers onto permanent contracts to bring security to the workforce and certainty to the business," he said.
"Transline must not be allowed to dodge its responsibilities or the back pay it owes for non-payment of the minimum wage at Sports Direct."
Sports Direct owner Mike Ashley recently sanctioned the appointment of a workers' representative to the firm's board in an attempt to improve the company's image.
Mr Ashley said he would walk away from the company if he failed to rectify it.
Last July, MPs accused the retailer of not treating its workers like humans and claimed its working practices were similar to those of a Victorian workhouse.