Mayweather vs. McGregor In Venue Standoff With BIG3

There's a fight of the century over the fight of the century ... with two major sporting events vying for the T-Mobile Arena on August 26th.

In one corner ... Mayweather vs. McGregor. When the fight was announced, Dana White and Floyd Mayweather stated it will take place at the Vegas venue.

Problem is ... Ice Cube's BIG3 basketball league already booked the location for the league championship game on the same night.

Our BIG3 sources tell us they have no plans to move -- they still have the venue booked and expect to play there on August 26th. The league even tweeted about it on Friday evening and T-Mobile has game tickets for sale on its site.

Sources connected to May-Mac tell us there are plans in motion to move BIG3 to the nearby MGM Grand Garden Arena ... it's just a matter of time before that becomes official.