Many in boxing think Miguel Cotto will be Pacquiao’s toughest challenge when they meet tonight in a highly anticipated 145-pound fight. But after trading punches, he has to please another kind of crowd when he takes the stage to sing with his band down the Las Vegas Strip.

His trainer would rather he concentrate on the immediate task at hand. But Freddie Roach understands by now that Pacquiao can’t keep still in the ring or out.

“I’m against the concert, of course,’’ Roach said. “But he does a lot of stuff. He’s multitasking all the time.’’

The stuff includes everything from helping victims of the recent typhoon in his native Philippines to starring in an action movie called, “Wapakman.’’ The father of four - who named one of his daughters Queen Elizabeth - has so many things going on all the time that even his ever expanding entourage has trouble keeping track.

None of it matters, though, if he doesn’t take care of business when he again carries the weight of a nation on his shoulders in the latest in a string of fights that have made him wildly popular far beyond his home country.

Pacquiao expects it to be his first knockout performance of the night.

“For me boxing is a kind of entertainment,’’ Pacquiao said. “You have to entertain people. You have to earn their trust.’’

Pacquiao has done just that in his last two fights, giving Oscar De La Hoya such a beating that he retired and dropping Ricky Hatton with one huge punch. He’s gone from being a top-tier fighter to being widely regarded as the best pound-for-pound fighter in the world, and beating Cotto would give him an unprecedented seventh title in as many weight classes.

It also would set up a bout with unbeaten Floyd Mayweather Jr. in one of the biggest fights in boxing history. That’s assuming, of course, that Pacquiao can focus on his most important duty of the night.

“I set aside everything that can distract my mind,’’ Pacquiao said. “This is the important fight of my life. To win seven titles means 20 or 30 years ago you won’t forget my name. Manny Pacquiao will still be there.’’

Though the fight will be for a piece of the welterweight title, it is being held at 145 pounds at the insistence of Pacquiao’s camp because Cotto is a natural 147-pounder and Pacquiao has fought only once above 140 pounds. The scheduled 12-rounder at sold-out MGM Grand arena will be on pay-per-view.

Pacquiao weighed in yesterday at 144 pounds, his heaviest ever, while Cotto was 145 at an event attended by some 7,000 fans.

The fight has the potential to be one of the most entertaining of recent big bouts, if only because Pacquiao fights in a frenetic style and Cotto loves nothing better than to move forward while throwing a relentless swarm of punches. But there are questions about Pacquiao’s chin against a bigger fighter as well as how much Cotto has recovered from the beating he took last year from Antonio Margarito.

“If we let [Cotto] win the first few rounds he’ll begin to think he can fight with Manny,’’ Roach said. “My job is not to let that happen.’’