But now is the perfect time for a sequel to settle the score between southpaws.

“Rayo” Valenzuela (15-3, 9 KOs) and "La Granada" De Los Santos (17-2, 15 KOs) are set to square off Sunday in a 10-round lightweight fight to headline Zuffa Boxing 08 on Paramount+ at The Cosmopolitan in Las Vegas.

“I expect a dangerous De Los Santos, just like he showed up the first time,” Valenzuela told The Ring. “De Los Santos is good, fast, strong, dangerous and has been talented his whole career. That's what I am preparing for.”

Valenzuela didn’t have any specific preparation for De Los Santos the first time they met in September 2024, as he took the fight on a day’s notice when the original opponent, Jezreel Corrales, was unable to secure a visa.

The rest is history, as De Los Santos stepped in as a mostly unknown fighter and picked apart Valenzuela in an entertaining fight that featured both tasting the canvas.

In the second round, after eating a heavy diet of punches, Valenzuela, who admittedly was hurt, scrambled the senses of De Los Santos with a counter left hook for a knockdown. But 30 seconds later, De Los Santos answered by dropping Valenzuela more viciously with a powerful combination.

Within 30 seconds of the third round, Valenzuela was knocked down again. He valiantly got back up, only to eat more unanswered shots, which forced the referee to stop the action.

“Any fighter who gets hit with an accumulation of punches is going to be in trouble, and that's what happened,” Valenzuela, 27, said.

“I was a young prospect, a kid coming in with my head up high, knocking people out. I checked off every box when it comes to fighting under bad conditions. Everything I shouldn't have done before a fight, I did and I paid the price. I didn't train properly. My abilities, too, in the ring. I was just reckless. I didn't have a good jab. I was standing too tall. I was just trying to catch him with big shots. It was bad all around.

“I should have known better. Maybe the people around me should have known better. But it's OK. He did his thing and it wasn't a fluke and I unfortunately suffered the consequences. Things happened, and I took a tough loss. It helped me. It was a great lesson and I grew from it as a person and fighter, and I am a much more dangerous fighter now.”

Valenzuela is 3-3 in his last six fights. After a controversial unanimous decision loss to Chris Colbert right after De Los Santos, Valenzuela righted the situation by cruising to a six-round stoppage victory in the rematch.

The win set him up nicely for a 140-pound WBA title shot against Isaac Cruz in August 2024, and Valenzuela wonia split decision. But the seesaw results continued again in the following fight as he was dominated by Gary Antuanne Russell for a unanimous-decision defeat in March of last year.

Valenzuela reshaped his team by signing a promotional deal with Zuffa Boxing, a managerial deal with Rick Mirigian and returned to longtime coach Mario Rodriguez after a two-fight run with Robert Garcia. Valenzuela was also trained and managed by Jose Benavidez Sr. in recent years.

Valenzuela resumed his career at lightweight in February and made his Zuffa Boxing debut in an entertaining 10-round unanimous decision win against Diego Nunez.

“For this fight, I have done the opposite of the first fight against De Los Santos. I’ve prepared. I've checked every box, so I’m ready to fight,” Valenzuela said. “I'm a different fighter than even after the Russell fight. I have a lot of different abilities in me. I can do a lot and it's going to be a totally different fight against De Los Santos. He's in for a surprise.

“I'm looking to win. I can't get greedy. That would be going back to my mistakes in the first fight. But I want to outclass him and make him pay.”

Valenzuela, from Renton, Washington, plans to make it a fight, unlike what De Los Santos and Shakur Stevenson displayed in their November 2023 encounter in what was by all accounts boring and forgettable.

“We have a map of De Los Santos’ full abilities across 12 rounds. I have a good sense of what he can and can't do,” Valenzuela said.

“You can still make De Los Santos miss and make him pay. I don't think it necessarily needs to be boring. That's not my style. None of my fights have been boring. I don't have to make it boring to win. I just have to be the best version of myself. I'm a fighter at the end of the day. I like to fight.”

De Los Santos has fought only once after the dull dance with Stevenson and scored a first-round stoppage during a December tune-up and homecoming in the Dominican Republic. He was supposed to fight Keyshawn Davis, who badly blew weight, in July and the fight was scrapped.

Valenzuela is hoping a dominant win against De Los Santos can give him a shot at Stevenson.

“If you let me pick who I can fight next after I beat De Los Santos, for me, it's Stevenson,” he said. “But first things first, I have to take care of De Los Santos and that's all I am thinking about right now.”

Manouk Akopyan is The Ring’s lead writer. Follow him on X and Instagram: @ManoukAkopyan