Upton has broken the records for most tries and try assists in a season during a sparkling first campaign since Newcastle released her on compassionate grounds.
"I don't think I've ever seen it, across both men's and women's programs, how wonderful she's been playing," Broncos coach Scott Prince said of his fullback.
The old firm now stands between Upton and a fifth grand final berth, with a win at Suncorp Stadium enough to put the hosts into their first decider since 2020.
Brisbane have the wood on the Knights this year; Upton set up two tries and scored one of her own in a 46-16 belting at McDonald Jones Stadium in August.
But Upton's co-captain Brigginshaw hasn't forgotten the booing her good mate received from a parochial crowd of 15,935 fans - the largest of the season to date.
"I'm really glad that we're not going back down to 'Newy' after what she copped last time," Brigginshaw said ahead of Sunday's game.
"She did expect that, (the fans) are very disappointed that she left. But in the end, she's a rugby league player and she deserves to make that choice on what's going to be best for her and her family.
"As a team, you never like to see one of your mates get booed in any form. There's no place for it. I wish it didn't happen."
Brigginshaw acknowledged that fans would only boo a player if they cared about the women's game.
"There's pluses and negatives towards that," the veteran playmaker said.
"But it was disappointing when we went down there."
Upton saw a silver lining in the last clash with Newcastle.
"My memories of the game is honestly just listening to my teammates," she said.
"You have to block out that noise sometimes. It's a positive thing if you think about it, they're getting fans to their stadium. That's always been the incredible part about Newcastle.
"Whether (the noise) is good or bad, there's people in the stands."
Upton credited premiership-winning former NRL playmaker Prince's wisdom as helping her take her game to new heights in 2025.
"His game plan is so simple, it leaves me a lot of room to work with," she said.
"When I sit and talk about different parts of footy, his knowledge is incredible. I'm always learning something each time I speak about something to him."
But the 28-year-old still feels she has improvement left in her as the season reaches its business end.
"That's the thing about the women's game, it's so new still. I'm still learning as a player," she said.
