The EFL is looking into whether Liverpool fielded an ineligible player during their game against MK Dons in the Carabao Cup on Wednesday.
Jurgen Klopp made 11 changes ahead of the 2-0 win, handing debuts to Caoimhin Kelleher, Rhian Brewster, Herbie Kane, and Harvey Elliott.
Sepp van den Berg, who signed from Dutch club PEC Zwolle in the summer, made his first start for the Reds off the bench.
There was also a rare appearance for Spanish midfielder Pedro Chirivella.
- How Liverpool lined up against MK Dons
- MK Dons 0-2 Liverpool – Match report and highlights
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Liverpool have admitted that there is a “potential administrative error pertaining to one of our players”.
A club statement adds: “We are working with the relevant authorities in order to establish the facts of the matter and will be making no further comment until this process is complete.”