Las Vegas bookies could be bettting their futures on this weekend's fight

Source: Connor McGregor / FACEBOOK

LAS VEGAS (AP) - If Conor McGregor manages to knock out Floyd Mayweather Jr., Las Vegas bookmakers will suffer the biggest single event loss in the history of sports betting.

McGregor fans are flooding casinos with small bets on the longshot mixed martial artist. He makes his pro boxing debut Saturday night against Mayweather, who is 49-0 and considered the best defensive fighter of his generation.

About 95 percent of the bets are on McGregor. Mayweather bets are much bigger - an average of $4,000 per bet to McGregor's $125 - but that isn't enough to cover the casinos' potential losses.

William Hill oddsmaker Nick Bogdanovich says his chain will suffer its worst lost ever if McGregor gets a knockout.