Despite age difference, Manny Pacquiao says he’s ready to take on Jessie Vargas on Saturday

New welterweight champion Jessie Vargas is 10 years younger than Manny Pacquiao, is nearly five inches taller and has a four-inch reach advantage and is confident enough to predict an upset in their title fight Saturday.

“I see [me] coming out with a big victory in front of the entire world in spectacular fashion and [surprising] everyone,” Vargas told reporters recently. “I am going to use every advantage I have in this fight.”

Vargas (27-1, 10 knockouts) will make the first defense of his World Boxing Organization welterweight belt Saturday night in Las Vegas against Pacquiao, who has won that same belt on three other occasions.

All that matters to Pacquiao (58-6-2, 38 knockouts) is that he has reverted in this training camp to the form that has allowed him to silence so many others who believed they had a formula to defeat him.

“A lot of fighters have said for many years that when they watch my style on TV — even from ringside — that it looks easy to handle. When you step into the ring with me, you’re surprised by the speed, my power, being heavy-handed,” Pacquiao said. “A heavy-handed boxer is different than a strong boxer.”

Although Pacquiao, 37, hasn’t scored a knockout since he stopped Miguel Cotto in the 12th round in 2009, he has adapted by relying on his still-effective punching speed in his 11 fights since.

The notable exceptions have some asterisks.

Timothy Bradley’s controversial split decision win in 2012 was avenged twice by Pacquiao, who knocked down Bradley twice in April.

Bulked-up Juan Manuel Marquez delivered an unexpected knockout over Pacquiao in 2012. Marquez had never dropped Pacquiao in their 36 prior rounds.

And Pacquiao went ahead with his big-money fight against Floyd Mayweather Jr. last year after suffering a training-camp shoulder injury that required post-fight surgery after Mayweather’s dominant decision win.

Otherwise, Pacquiao has looked impressive in his wins over Antonio Margarito in 2010, a 2011 knockdown of formidable Shane Mosley and six knockdowns while winning a decision over Chris Algieri in 2014.

“Many of those [opposing] game plans haven’t worked out so well,” Pacquiao trainer Freddie Roach said. “I know there’s some things being said by [Vargas] and his [trainer] … about their plan, but we have ours, too, and my fighter is as sharp as a tack today.

“I just have to maintain him and keep him right where he is.”

Roach said Pacquiao’s speed is typically the first thing to startle foes, which is why the seven-time trainer of the year was so pleased with what he’s seen from Pacquiao in training camp.

“He showed every bit of his speed today,” Roach said last week. “He’s as good now as he ever was, in my mind.”

Longtime sparring partner Ray Beltran, a former 140-pound title challenger, was buzzed by a Pacquiao punch despite headgear.

“He stung me with a left,” Beltran said last week. “Once Manny gets him, Vargas won’t be able to keep up. Manny is poison for Vargas’ style. [Vargas] is a brawler. He likes to fight, but Manny takes a punch very well. He’s strong and keeps throwing punches.”

Unbeaten super-lightweight Jose Ramirez of Fresno spent five weeks of training and 56 rounds of sparring in the Philippines with Pacquiao, who trained in the late afternoon following his work as a first-term senator in the country.

“Manny will surprise Vargas with his speed and movement,” Ramirez said. “I throw a lot of punches, and I’d never been tired in the ring, but Manny made me as tired as I’ve ever been from the hips down through three rounds because he keeps me thinking and moving and tense, waiting for his explosive punches.”

After seeing how he’s performed this camp, Roach is pressing Pacquiao to impressively finish off Vargas and call out the retired Mayweather for a rematch.

Going for the kill “is the key,” Roach said.

“I’m thrilled with his performance [this camp]. He’s still all there. He doesn’t care how old he is.”

lance.pugmire@latimes.com

Twitter: @latimespugmire