Tony Harrison’s resume is undeniably better than Carlos Ocampo’s.

Detroit’s Harrison is a former WBC super welterweight champion and the only fighter to defeat Jermell Charlo, who has been boxing’s undisputed 154-pound champion over the past 13 months. Tim Tszyu respects Harrison and his accomplishments, but the WBO interim junior middleweight champion still anticipates a more difficult fight from Carlos Ocampo on Sunday afternoon than Harrison gave him three months ago.

“I think it’s a different challenge,” Tszyu told BoxingScene.com. “I think when it comes to the actual fight, it’s gonna be a tougher fight. You’re gonna be more tired, it’s gonna be more physical, rather than more of a thinking type of fight with Tony Harrison. Every fight is a different challenge.”

Tszyu handled Harrison commendably March 12 at Qudos Bank Arena in Tszyu’s hometown of Sydney, Australia.

On paper, Harrison was the toughest opponent of Tszyu’s six-year professional career. In the ring, however, Tszyu (22-0, 16 KOs) mostly remained in control until he dropped and stopped Harrison (29-4-1, 21 KOs) in the ninth round of their 12-round title fight.

The 28-year-old Tszyu senses that he has earned more respect in the boxing world by beating Harrison so impressively. He expects Mexico’s Ocampo (35-2, 23 KOs), who promised “a war” during their final press conference Friday, to provide plenty of pressure in what could become a grueling fight if Tszyu allows it.

“Stylistically, I think it’s a tough fight due to just his style,” Tszyu said. “He’s tough and he’s open, but at the same time he’s not. And you don’t expect the shots from all different angles. That’s always hard when you don’t have a conventional boxer in front of you.”

The 27-year-old Ocampo has gone 13-1 since unbeaten IBF/WBA/WBC welterweight champion Errol Spence Jr. (28-0, 22 KOs) stopped him in the first round almost five years ago at the Dallas Cowboys’ training facility, Ford Center at The Star, in Frisco, Texas. Ocampo’s lone loss during that stretch was a 12-round, unanimous-defeat to then-unbeaten Sebastian Fundora (20-1-1, 13 KOs) in a fight for Fundora’s WBC interim super welterweight title last October 8 at Dignity Health Sports Park in Carson, California.

Handicappers have still established Tszyu as an 14-1 favorite in a fight that will headline a pay-per-view show Sunday afternoon in Australia ($59.99; 12 p.m. AEST).

Showtime will televise Tszyu-Ocampo live Saturday night in the United States (11:30 p.m. EDT; 8:30 p.m. PDT). The network’s coverage from Australia will begin with a 12-round IBF elimination match between junior featherweight contenders Ra’eese Aleem (20-0, 12 KOs), of Muskegon, Michigan, and Sam Goodman (14-0, 7 KOs), of Albion Park, Australia.

If Tszyu conquers Ocampo, he is expected to challenge Charlo for his IBF, WBA, WBC and WBO belts later this year. Tszyu told BoxingScene.com that his shot at Charlo’s championships could be rescheduled for October, but the mandatory challenger for Charlo’s WBO crown hasn’t been told a date or site for their fight.

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