For Freddie Roach, the past few weeks have been just another crazy adventure on the Manny Pacquiao express. But the trainer of the world’s most popular, and many believe best, boxer has learnt to expect the unexpected.

Pacquiao challenges Miguel Cotto for the WBO welterweight title at the MGM Grand Garden Arena tonight, another step towards sporting immortality as he attempts to win a sixth world title in a career that began ten divisions lower at light-flyweight.

Remarkably, though, the bout is not the only thing in Pacquiao’s diary tonight.

“He’s booked a concert for after the fight at the Mandalay Bay,” Roach said. “They are paying him $100,000 [about £60,000] to play 13 songs. When I heard, I said, ‘Manny, what are you doing? This is a hard fight.’ He just said, ‘I can do both.’

“Every night, after training, he goes off to rehearsal. At least when he does his music, he’s calm, he’s relaxed and it gets his mind off the boxing.”

But Roach has become accustomed to the strange ride with Pacquiao, which includes fans thrusting babies into his arms for photos. While Pacquiao is the most famous face in the Philippines, Roach comes in third, just behind Gloria Arroyo, the country’s President.

“I never thought it would be like this,” Roach said. “I’m just about famous enough to have fun with it, but I can still go to the mall, which Manny can’t.

“He is exactly the same guy he always was. He’s got more money, but when he comes in, he’s not cocky, he works as hard as he did the day I met him.

“I tell him off all the time and people say, ‘Tell him off like that again and you’ll get fired.’ But I have to do what is best for my fighters. I’m honest with them, I’m honest with everyone in life and if they fire me, they fire me.” There seems little prospect of that happening. Pacquiao, 30, said at Wednesday’s head-to-head press conference that he had promoted Roach. “Before, I called him coach Freddie,” Pacquiao said. “Now, I call him my master.” Roach says it is an honorary title. The camp, however, has not been without problems. For tax reasons, Pacquiao began it outside the United States, in Baguio City in his homeland. But two typhoons hit the Philippines, the second dumping 28in of rain on Baguio — almost 5,000ft above sea level — creating a natural disaster.

For Pacquiao, it meant that he could not do his roadwork, forcing him to do lengths of a pool, even though he can barely swim. The camp moved to Manila, but things got worse.

“Baguio for the first weeks was no problem, Manila for the four days sucked,” Roach said. “His focus wasn’t there because everyone wanted to pull him this way and that.”

At last night’s weigh-in, Pacquiao was one pound lighter than Cotto. The Filipino tipped the scales at 10st 4lb, with Cotto right on the contracted weight at 10st 5lb.

Some believe that the bout could become the biggest pay-per-view boxing event in history in the US, challenging the 2007 Floyd Mayweather Jr-Oscar De La Hoya contest, which is remarkable considering that the boxers come from the Philippines and Puerto Rico and neither speaks English as his first language.

After the boxing and singing, Pacquiao appears as a masked superhero in Wapakman, a film released in his homeland this month, wearing a red spandex suit. “That suit is really funny,” Roach said. “With all that money spent, they should have got him a better suit.”