A suspended Erik Pieters was accidentally named in the Burnley team for their FA Cup fifth round defeat to Bournemouth on Tuesday.
The Clarets were beaten 2-0 at home by the Championship club, but they could have faced disqualification from the competition had Pieters played.
Burnley boss Sean Dyche revealed a member of staff at Bournemouth alerted him to the selection gaffe, with the Clarets admitting their ‘administrative error’.
He said: “It wasn’t disruptive. It was just a simple admin error.
“We have people who keep an eye on situations, unfortunately it got away from that moment where someone found clarity.
“The rules have changed this year with the booking situation and the number of games in the FA Cup. It was just a clear oversight.
“To be fair to Bournemouth, they flagged it and mentioned it, so credit to them for a bit of gentlemanly conduct.
“We jumped on it straight away and people at our club held their hands up in the right slots.”
Pieters was ineligible to play after picking up two yellow cards in previous FA Cup wins over MK Dons and Fulham this season.
In his absence, 21-year-old Liverpool academy graduate Anthony Driscoll-Glennon was given his full Burnley debut, with goals from Sam Surridge and Junior Stanislas ultimately handing Bournemouth victory.
Cherries caretaker boss Jonathan Woodgate praised his colleague for spotting the Pieters mistake in the line-up.
He said: “Fair play to the staff who did it and told Burnley. We all want a fair game, so I thought it was important we did that.
“I think it was Anthony, our press officer, who did it. It’s good sportsmanship at the end of the day.”