When Manny Pacquiao faces the lumbering slugger Brandon Rios on Saturday in Macau, China, the Filipino boxing superstar will go against a guy with just one loss.

And that loss came at the hands of Denver’s Mike Alvarado. So Alvarado, and his trainer Shann Vilhauer, have a unique insight into how Pacquiao can beat Rios.

Rios fell to Alvarado in March, in the second of a back-to-back series, after Alvarado used a boxing skill edge to win a unanimous decision. It was Rios’ first career loss, after he handed Alvarado his first career loss last year.

“The important thing is to keep that strong mental (attitude),” Alvarado said of how Pacquiao should face Rios. He was talking in a video interview with broadcaster Rich Marotta along radio row in Las Vegas. “Of not giving in to his style, not giving in to going to war with him, giving in to a slugfest.

“Rios did that with us in the first fight and it gave him more of an opportunity to land that big shot.”

Alvarado is coming off a 10th-round technical knockout loss against Ruslan Provodnikov last month. Alvarado was given a bout against the Russian in Colorado after Rios landed a bout against Pacquiao.

On its surface, it seems Pacquiao has a skill advantage over Rios. Pacquiao remains one of the better boxers in the sport, despite some fade in his game that showed up in a knockout loss to Juan Manuel Marquez last December.

Rios, on the other hand, has earned a reputation has a hard-hitting slugger who stalks opponents in a straight-ahead style. But Vilhauer, who was in Alvarado’s corner for both bouts against Rios, said Rios is an underrated boxer.

“Brandon’s a better boxer than people give him credit for,” Vilhauer said. “Problem is, he’s a Pacquiao-level fighter, but not a Pacquiao-level boxer. Pacquiao is that good.

“Still, Rios will get to Pacquiao. At some point, Brandon will touch him. He’ll walk him into hard shots.”

The 27-year-old Rios (31-1-1) will be fighting for the first time outside the United States, in one of the first major boxing bouts held in China since Communist Party Chairman Mao Zedong banned boxing in the 1960s.

Pacquiao, 34, has compiled a large boxing resume with a record of 54-5-2. But he’s also a congressman in the Philippines, where Typhoon Haiyan recent ravaged the coastal city of Tacloban killing more than 5,200 people.

Both Alvarado and Vilhauer predicted a late-round stoppage victory for Pacquiao against Rios in a fight similar to Pacquiao’s victory over Antonio Margarito in 2010.

“Brandon’s just got to bring the pressure the whole time,” Vilhauer said. “That’s what Mike did when he sparred with Pacquiao (in 2009) and he had some success against him. He has to be light on his feet, don’t just plod.”

Nick Groke: 303-954-1015, ngroke@denverpost.com, twitter.com/NickGroke