One is on the rise. The other might be on a slight decline. Yet they intersect at a place in their careers that promises an intriguing fight on HBO.

Andre Berto defends his WBC welterweight title against Luis Collazo on Saturday at the Beau Rivage Resort & Casino in Biloxi, Miss.

Berto, 25, is one of the quickest, most-explosive punchers in boxing but hasn’t faced a significant test. Collazo, a 27-year-old former titleholder, has had two major setbacks the past few years but remains a legitimate threat to anyone in the division.

It’s not a megafight ÔǪ but it’s a fight.

“On paper, this is the toughest fight of Berto’s career – by far the toughest,” said Carl Moretti, matchmaker for Berto’s promoter Lou DiBella.

Berto (23-0, 19 knockouts) is 5 feet, 8¾ inches of fast-twitch muscle. His punches come in rapid succession and do considerable damage, as his 83-percent knockout ratio indicates. And, to make matters worse for his opponents, he can box.

The 2004 Olympian for Haiti, the native land of his parents, has not even been in a close fight as a professional. Four opponents went the distance with him but each lost badly on the cards.

Berto's only taste of adversity occurred when he was dropped by veteran Cosme Rivera in the sixth round of their 2007 fight. Berto survived the scare and went on to win a lopsided 10-round decision.

Any way you look at it, his perfect run is a significant accomplishment. At the same time, Berto, who stopped Miguel Angel Rodriguez last June to win the vacant title, hasn’t beaten a big-name opponent.

The biggest might be Steve Forbes in Berto’s last fight, in September. However, Forbes, tough but lacking power, never really had a chance to win.

Berto had hoped to fight Shane Mosley in what would’ve been an enormous step up in both name recognition and the challenge Mosley would’ve posed. In the end, though, Mosley decided to fight for Antonio Margarito’s WBA version of the title instead on Jan. 24 in Los Angeles.

“I used to be sour about it,” said Berto, referring to criticism of his choice of opponents. “Now, I try to look at it as a good thing. I just came out of the ’04 Games and people already want me to fight the best in the division. They feel those are the only people who can test me.

“It’ll happen this year; I’ll step up to the big guys ÔǪ if everything goes well Saturday.”

Enter Collazo, the mandatory challenger for Berto’s title.

The tough, well-schooled New Yorker doesn’t have Mosley’s fame but he might be as good – or even better – than the 37-year-old former four-time world titleholder at this point.

A victory over Collazo probably wouldn’t completely silence critics who question Berto’s resume but it certainly would help.

Collazo (29-3, 14 KOs) almost pulled off a monumental victory over then-WBA welterweight titleholder and unbeaten Ricky Hatton in 2006. The two engaged in an entertaining, give-and-take fight in Boston that Hatton ultimately won by a narrow margin, a decision many questioned.

“He beat Hatton even though his hand wasn’t raised,” Moretti said.

Collazo then lost a one-sided decision to Mosley in 2007 after breaking his hand early in the fight. He has won twice since recovering from the injury to earn a shot at Berto and another belt.

He might not get too many more chances in his career.

“I had to fight my back to the No. 1 (challenger) position but here I am, thank God,” Collazo said. “ÔǪ Berto is a good fighter. He’s strong and fast. I see some flaws I can capitalize on, though.

“He’s in for a rude awakening. He hasn’t fought anybody like me yet.”

Berto seems to recognize that.

Yes, he’d rather be preparing to fight Mosley in a week or one of the other stars in the division. However, he knows that he must get through a determined fighter in Collazo for those big-time matchups to happen.

“He’s a slick fighter, a southpaw,” Berto said. “He’s the type of fighter that even if you beat him, you don’t always look good doing it. Nobody wants to fight fighters like that. I proved I’m willing to do it, though. Steve Forbes is the same way, difficult, always making you look bad.

“I’ve trained seriously (for Collazo). He’s the type of guy who can spoil your party.”