With 11 of their top 30 players unavailable, mostly due to injury, the Broncos had to go to the NRL for special dispensation to play train-and-trial back-rower Riki, who's no relation to starting second-rower Jordan Riki.
Riki, 28, has played three NRL games for Penrith and represented Maori All Stars, but is currently playing for Souths Logan in the Hostplus Cup.
He's been named on the bench, as has Semu, a giant 110kg and 194cm prop who has been starring for Burleigh Bears.
Centre Kotoni Staggs (foot) and fullback Jesse Arthars (calf) were injured in Brisbane's gallant 21-20 win over Wests Tigers away on Saturday night.
They have been named to take on the Bulldogs at Suncorp Stadium on Friday night ahead of proving their fitness.
Captain Adam Reynolds, the star of the win over the Tigers, said Semu - who was on the bench but did not play in Campbelltown - was ready to step up on his NRL debut.
"He is a young fella who has been working hard in the background," Reynolds said.
"He has had to sit and wait on the bench once or twice and hasn't gotten on due to circumstances.
"I'm sure he will feature at some stage over this game. He looks up to blokes like Payne Haas, Patty Carrigan and Corey Jensen, and he is always striving to get better himself.
"It was great to see his family down there in Sydney. I'm sure they will all be up here in Brisbane waiting for him to get on the field."
Reynolds said the Broncos prided themselves on winning against the odds and were prepared to do so again.
"It's always a good situation to be the underdog," Reynolds said.
"There is less pressure and no-one expects you to go out and perform and win.
"But when you have a belief amongst the group that you can go out there no matter who is in the jersey to get the job done, it's a pretty powerful thing."
Reynolds is showing his true leadership credentials by steeling the team to fire while understrength. He said there would be "no excuses" for a sub-par display against the Bulldogs and backed every member of the side to do the job.
"It takes a squad to win premierships. It's not just the 19 that turn up on game day, there's a lot that goes on behind the scenes," he said.
"You only have to look at the top teams performing well, the players underneath are preparing to their best of their abilities and that shows on weekends.
"It's a great opportunity for us as a squad to showcase some of these players who may not get that regular first grade time. But we are confident that whoever steps into the jersey can do the job."