Floyd Mayweather Jr and Manny Pacquaio clash at the MGM Grand in Sin City on Saturday night in a fight worth £300m.
But police and security staff are also worried about possible fights outside of the ring as around 150,000 to 200,000 fans descend on the boxing capital this weekend to sample the atmosphere.
The 16,500-seater MGM Grand is sold out and there are fears that ticketless and boozed up fans could start trouble if the big fight atmosphere turns sour.
So extra security has been drafted in from outside of Vegas to keep control.
This is the second biggest event of the city’s year, with only New Year’s Eve bringing more visitors to the Strip.
Lieutenant Roxanne McDarris is in charge of operations and leading the way to ensure the weekend passes off without major incident.
She said: “We really haven’t had to deal with a sporting event of this scale.
“It’s important people are aware of their surroundings and know what’s happening around them.”
Sin City has a bad history of violence when big sporting events take place.
The NBA’s 2007 All-Star weekend had four shooting incidents and 400 arrests.
And boxing has had its own bad night when in 1996 Mike Tyson fought Bruce Seldon at the MGM Grand.
Rapper Tupac Shakur was involved in a fight in the hotel lobby and later that night elsewhere he was murdered in a drive-by shooting. The MGM Grand are also bringing in extra staff to help ensure no problems.
MGM’s vice president of security Tim Jeffery said: “We’ll have a higher-than-usual number of security employees.
“That will be obvious to anybody who visits the property.”