Manny Pacquiao has gone from fighting an undefeated, unified welterweight champion commonly considered one of the sport’s top five fighters, pound-for-pound, to boxing a secondary title-holder with four losses on his record.

The 42-year-old Pacquiao insists, however, that he considers Yordenis Ugas every bit as threatening as Errol Spence Jr. It’s a typical tact favored fighters take when they discuss late replacements, though odds-makers have installed Pacquiao as only slightly less than a 3-1 favorite versus Ugas.

Spence was listed as more than a 2-1 favorite to beat Pacquiao, who will square off against Ugas in a FOX Sports Pay-Per-View main event August 21 at T-Mobile Arena in Las Vegas.

“What I can say to the fans is this fight is not an easy fight,” Pacquiao said Wednesday during a virtual press conference. “Ugas is a champion. He took my belt, and we have to settle it inside the ring. You know, I’ll never take him lightly for this August fight because Ugas is a kind of fighter you cannot underestimate. This is gonna be a good fight, also. Ugas and Spence is similar and same [height], so nothing changed. Just different style in southpaw and right-handed.”

The 35-year-old Ugas (26-4, 12 KOs) was supposed to defend his WBA “super” welterweight title against Argentina’s Fabian Maidana (18-1, 13 KOs) on the Spence-Pacquiao undercard. Maidana suffered a cut during sparring that would’ve prevented him from facing Ugas even if Ugas wasn’t elevated into the main event.

The Cuban champion found out almost simultaneously Monday that Maidana was out of their fight and that he would replace Spence as Pacquiao’s opponent. Spence learned Monday during an extensive eye exam ordered by the Nevada State Athletic Commission that his torn right retina required surgery, which was performed Wednesday in Dallas.

Ugas, meanwhile, will attempt to legitimize himself as the WBA’s primary welterweight champion.

The Miami resident defeated Abel Ramos (27-4-2, 21 KOs) by split decision in a 12-rounder last September 6 at Microsoft Theater in Los Angeles to become the WBA world welterweight champ. The WBA promoted him to “super” champion late in January because Pacquiao (62-7-2, 39 KOs) had been inactive since he won the WBA “super” title from Keith Thurman (29-1, 22 KOs, 1 NC), who lost a split decision to Pacquiao in July 2019.

“This means the world to me,” Ugas said Wednesday. “I’m fighting not for the money, but for my legacy, for my country, for my own story that’s gonna be told. That’s what it’s about to be. This is the most important fight of my life.”

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