Lenin Castillo had almost twice as much time to prepare for his fight with Callum Smith on Saturday night than his shot at Dmitry Bivol’s light heavyweight title.

Castillo barely was given three weeks’ notice when he challenged the unbeaten Bivol for his WBA 175-pound crown in October 2019 in Chicago. Bivol beat Castillo convincingly in their 12-rounder, by scores of 120-107, 119-108 and 119-108.

The Dominican Republic’s Castillo (21-3-1, 16 KOs) is much more confident as he prepares to meet Smith (27-1, 19 KOs) on the Anthony Joshua-Oleksandr Usyk undercard at Tottenham Hotspur Stadium in London.

“The difference with this fight is that I’m coming well-trained, where with Bivol I wasn’t,” Castillo told BoxingScene.com. “Basically, it was like, ‘You’re fighting in two, three weeks,’ and that was it. I took the fight and I lasted 12 rounds with the champion. I wish I was well-trained, but it was a world championship bout and you never know what could happen. I do have power, you know, so why not? It was about the opportunity.”

Castillo considers his power an advantage against Smith, who will fight in their 10-rounder for the first time since Canelo Alvarez dominated him in their 12-round, 168-pound championship match December 19 at Alamodome in San Antonio. The 6-feet-3 Smith moved up to light heavyweight in the aftermath of his first professional defeat to Mexico’s Alvarez (56-1-2, 38 KOs), whereas Castillo has fought at or around the light heavyweight limit of 175 pounds throughout his 11-year pro career.

“I think I’m a bigger puncher than Callum Smith,” Castillo said. “This is my natural weight here. There is different power at 175 than at 168.”

The 33-year-old Castillo considers Smith, 31, a comparable opponent to Russia’s Bivol (18-0, 11 KOs).

“They have different styles of boxing, of course,” Castillo said, “but they are basically on the same level of the sport.”

Castillo won his only bout since Bivol beat him July 21, when he stopped Venezuela’s Ronald Gonzalez (8-1, 8 KOs) after the fourth round of their scheduled 10-rounder in Santo Domingo, Dominican Republic, Castillo’s hometown. Castillo realizes, of course, that he’ll have to be a lot better Saturday night to beat Liverpool’s Smith than he was when he boxed Bivol.

“I’m ready for the fight,” Castillo said. “I know this is a big fight. I know that if I win this fight, I’ll fight for a world title or a rematch with Bivol.”

Smith-Castillo will be part of a Sky Sports Pay-Per-View show in the United Kingdom and Ireland (6 p.m. BST; £24.95). DAZN will stream it in the United States (1 p.m. EDT) and in more than 200 other countries and territories.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.