LOS ANGELES — Luke Campbell cracked a smile and let out a little laugh.

There he was, in the process of explaining just how he’ll upend Jorge Linares on Saturday and take home THE RING’s lightweight championship, when it started.

“There’s only oneeeeeeeeeee, Luke Campbell! Oneeeee Luke Campbell! He’s marching along, singing a song, walking in a Campbell wonderland.”

And on and on it went. Even at the press conference two days ahead of the HBO bout, his supporters were there to cheer him with a familiar song from home.

He expects about 120 friends and family from Yorkshire, England, to be there singing again at The Forum in Inglewood, California. Hundreds more fans, he believes, will make the trip, too. He’ll need all the support he can muster, for he’s taking a tremendous jump in class.

To date, Campbell, 29, has feasted mostly on European-level fighters and was even defeated by one. Yvan Mendy scored a knockdown of Campbell en route to a split-decision victory in a major upset.

Since the December 2015 setback, Campbell says he’s learned a harsh but valuable lesson (more on that later). And despite the Olympic gold medal he won in 2012, he knows he’s been counted out by many.

“That will make it all that much better when I come out winning,” Campbell (17-1, 14 knockouts) told RingTV.com. “I’m improving my boxing skills more; adapting it to a pro style; adapting to 12 rounds. I am a 12-round fighter.”

When you’re a top amateur for so long, it’s easy to fall into the trap of the style that got you there. But in the pros, you must punch with power, at least enough to gain your opponent’s respect and keep him at bay.

Campbell knows he’s now punching “much harder” and knows he possesses the “speed, accuracy and timing” to get Linares out of there.

But he wasn’t always brimming with confidence. Not after the unexpected defeat to Mendy. He found himself on the canvas in Round 5, and eventually, on the losing end.

How could he, Luke Campbell, owner of an Olympic gold medal after a decorated amatuer career and filled with promise, be defeated by a man with four defeats to middling fighters?

Campbell was beyond upset. Depressed. How could he have allowed this to happen?

Well, for starters, he wasn’t fit to compete, And he only blames himself. Eight days before the fight, Campbell woke up feeling out of sorts. He had a virus. He was overtrained; weak; tired. Campbell takes full responsibility for not withdrawing from the fight, and vows to never again fight at anything less than 100 percent.

But it took quite some time before he returned to the proud fighter you see today. He’s won five consecutive bouts since the loss, two of those stoppages of former champions (Argenis Mendez and Darleys Perez). And he’s earned this 135-pound title shot.

“I was sad that I let people see a weak version of me,” Campbell said. “It had nothing to do with boxing ability; nothing to do with having to rebuild and restart again. Nothing to do with any of that. I just let someone see me in a weak moment and that will never happen again.”

Eventually, he crawled out of depression and now is on the cusp of his first world title shot. It’s a long way from home, but the occasion is just right.

“I believe I’m ready now,” he said. “Not in a month; not in six months,;not in a year. I believe this is my time now.

“I’ve seen good fighters crumble when the pressure gets to them; I’m the opposite way. I like the bigger crowd. This is what boxing is all about. Being in the main event and fighting for a title.”

Mike Coppinger is the Senior Writer for RingTV.com. Follow him on Twitter: @MikeCoppinger