The tournament took place in New Jersey, where handicappers started with a $5,000 bankroll on the DraftKings Sportsbook mobile app, playing for a share of a $2.5m jackpot.
On the final day of the tournament, there were only two NFL play-off games players could bet on, according to Legal Sports Report.
However, as the New England Patriots beat the San Diego Chargers, the match overran and nearly overlapped with Philadelphia Eagles’ clash against New Orleans Saints.
Consequently, several bettors could not place a wager on the second game in time, having their entire bankroll in play during the first match before their winnings were paid out.
A DraftKings spokesperson released the following statement: "The first-ever Sports Betting National Championship was an incredibly thrilling event. We recognise that in the rules the scheduled end of betting coincided very closely to the finish of the of Patriots-Chargers game.
"While we must follow our contest rules, we sincerely apologise for the experience several customers had where their bets were not graded in time to allow wagering on the Saints-Eagles game. We will learn from this experience and improve upon the rules and experience for future events."
