Leniu will not play for the Tricolours in Friday night's blockbuster, as he serves the last match of his eight-game ban for calling Mam a "monkey" in Las Vegas.
Tensions between the two teams remained high after the slur, including a late-night verbal altercation between Leniu and several Broncos at their US hotel.
The two sides were also then forced to share a flight home together, before Leniu fronted the NRL judiciary the following week.
Mam is also no certainty to play, with Brisbane to reassess his finger injury at training on Tuesday.
Ezra Mam in action against the Roosters during Brisbane's controversial ​Las Vegas clash. (HANDOUT/NRL PHOTOS)
The Indigenous star has said he is prepared to meet with Leniu in the future to accept an apology, after rejecting a request to do so last month.
Haas himself provided a statement to the NRL over the slur, before Leniu admitted in his judicial hearing to saying "f*** up, monkey" to Mam during an on-field exchange.
But Haas insisted that would not be forefront in players' minds on Friday.
"I don't think (it'll be an issue)," he said.
"I wasn't around (in the Vegas corridor) so I'm not sure what happened, if there was any bad blood. But I'm pretty sure they've buried the hatchet there.
"Our team is pretty good for this kind of stuff, we know it's just another game of footy.
"It's going to be a physical game anyway, so (the history) doesn't really matter."
Haas was also adamant the Broncos' 20-10 defeat to the Roosters in Vegas would be irrelevant with Brisbane back playing on the regular-sized Suncorp Stadium.
The Broncos appear to be building into their season, while the Roosters enter on the back of a 60-18 win over St George Illawarra after a shaky start to 2024.
"We didn't play our best (in Vegas). But it was round zero. We're improving now and going week by week," Haas said.
"We haven't had our full team. But it's good to have most of the boys back now and just focus on improving each week."
Payne Haas carries two Wests Tigers defenders with him at Campbelltown Stadium. (Brett Costello/AAP PHOTOS)
Haas is arguably the most vital of Brisbane's returnees, running with power in his comeback from a knee injury against Wests Tigers on Saturday.
The 24-year-old played limited minutes, but ran with far greater impact than before his injury this year in a promising sign for NSW ahead of State of Origin I on June 5.
"At the start of the year I didn't feel like myself," Haas admitted.
"I had a big pre-season, I trained hardest I ever have and felt like I was letting myself down the first two games.
"It held me back a little bit with running. I felt like I was at 80 per cent most of the time. I feel good now, physio has done well. Just really pleased with it."
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