Despite retiring after his victory over long-time rival Amir Khan in February last year, Brook has now sounded out a return to the sport and is reportedly "desperate" to face the winner of this weekend's clash.
The 36-year-old decided to hang up his gloves after comfortably beating Khan with a sixth-round stoppage, but has continued to train since then.
"Kell will be there on Saturday. He's desperate for the winner of that fight. He wanted the Eubank fight after the Khan fight," promoter Ben Shalom told Sky Sports.
"He feels he wants the winner of this fight whether that's Liam Smith or whether that's Eubank Jr.
"There is a rematch clause, so if Liam does win Eubank will have the option with that one. But there'll be massive fights for whoever the winner is.
"Eubank Jr is a big star. Especially outside the heavyweight division there's not many like him. There was always the question mark, especially since he fought George Groves, can he win a world title? Was he actually world level?"
Speaking to TalkSport in October, Brook was already giving signals that he wanted to fight Eubank Jr at some point in the near future.
"It's a fight that does excite me, I won't lie," Brook said.
"If it makes business sense then who knows? But I'm not saying to you now, 'Eubank, be ready I'm coming for you,' I'm not saying that.
"I'm saying 'who knows'?
"If I'm starting to train again and I get that excitement where I want to come back, then those fights are there."
Eubank Jr goes into the fight as bookies' favourite given his experience with big fights, including notable wins against the likes of James DeGale (36) and Avni Yildirim (31), but many still point to his defeat against George Groves (34) with concerns over his big-fight ability.
Slight underdog Smith is a former WBO champion in his own right, with many pundits suggesting he is more than capable of upsetting the odds as the Liverpudlian targets a return to the upper echelons of the sport.