The Pacquiao vs Mayweather jnr fight will most likely take place in Las Vegas.

Promoters of the megafight between Manny Pacquiao and Floyd Mayweather jnr bout cancelled a trip to Dallas on Wednesday, an apparent sign that the new Cowboys Stadium won't host the big showdown next year.

The trip was called off at the last minute because Mayweather's camp apparently decided he didn't want the fight at the new billion-dollar stadium that is home to the Dallas Cowboys.

The move left the MGM Grand arena in Las Vegas as the favorite to host the fight, expected to take place on March 13.

Co-promoter Bob Arum said he was surprised by the decision from Golden Boy chief executive Richard Schaefer, to call off the trip to Texas.

Both fighters have reportedly agreed to terms for the bout, but neither has signed contracts.

Cowboys owner Jerry Jones said last week he hoped to bid for the fight for his stadium in suburban Dallas, while representatives of the Superdome in New Orleans were also interested.

An official at Staples Center, home of the NBA's LA Lakers, told the Los Angeles Times on Wednesday that the arena had made a $20 million-dollar offer to host the fight.

However, the Los Angeles venue would probably need to offer more than a Las Vegas venue because California imposes state taxes that the fighters would have to pay, and Nevada doesn't.

Mayweather, 40-0 with 25 knockouts, was regarded as the world's top pound-for-pound fighter before a 19-month layoff that ended last September.

Pacquiao, 50-3 with 38 knockouts, staked his claim on the pound-for-pound crown in Mayweather's absence by knocking out England's Ricky Hatton in the second round last May and stopping Miguel Cotto in the 12th round last month.

The Pacquiao-Mayweather showdown could bring record profits to break the mark set by Mayweather's split-decision victory over Oscar de la Hoya in 2007.

The fight is expected to be officially launched with a press conference in January in New York.

Pacquiao is running for congress in his homeland and elections are in May, which scuttled plans for a May date for the fight.

The Filipino star is expected to begin training in his homeland and complete his workouts at trainer Freddie Roach's Hollywood gym.