A representative from Bournemouth saved Burnley by telling them that they had put the ineligible Erik Pieters in their starting line-up prior to Tuesday's FA Cup fifth-round clash, Clarets manager Sean Dyche said.
Pieters had picked up bookings in the previous two rounds of the competition, meaning he was suspended for the game against the Championship side.
The Dutchman was replaced before kick-off by Anthony Glennon, with the Cherries going on to win the game 2-0 and advance to the quarter-finals.
What did Sean Dyche say about the mistake?
After the match, the Burnley boss said: "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.
"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."
Who advised Burnley about the mistake?
Bournemouth caretaker manager Jonathan Woodgate said the club's head of media Anthony Marshall recognised the error and made Burnley aware.
"Fair play to the staff who did it and told Burnley," Woodgate said. "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."
What would have happened if Pieters played?
Burnley could have faced disqualification from the FA Cup had the full-back participated in the match, or they could have been forced to replay the game.
Clubs in the past, including Bury, Bradford City and Chesterfield have been hit with such punishments for fielding ineligible players.