Jelavic will make his Hull debut at Norwich on Saturday having signed from Everton for a club record fee that could rise to £7.5million, while West Brom forward Long had a medical on Thursday and is on the verge of joining for a similar fee.
The double move is a considerable coup for a side who were plying their trade in the second tier last season but, instead of being praised by fans, Allam is under fire for his controversial plans to rebrand the club as Hull Tigers and his recent threat to walk away if it is stymied.
Bruce has attempted to play peacemaker between the two parties at various times this season, but feels Allam's financial backing says everything about his commitment to Hull.
"It's a colossal sum of money for us," he said.
"He (Allam) doesn't have to make any more statements than what he has just done. The most important thing for me is the two players we are bringing in to wear the shirt, who will significantly add to the squad and make us better and bigger and keep us in this division for the next few years at least."
Hull hope to heap more woe on struggling Norwich tomorrow with Canaries boss Chris Hughton vowing to fight on despite a run of six league games without a win being exacerbated by a midweek FA Cup replay drubbing at Fulham.
Hughton said: "We certainly understand and respect the opinions of the supporters. It is their club and one thing I can guarantee is that we are working as hard as we can to be looking upwards."
Southampton travel to improving Sunderland boosted by the insistence of boss Mauricio Pochettino that he will not walk away from the club despite the departure of executive chairman Nicola Cortese.
The Saints manager stopped short on Thursday of committing beyond the end of the current season, but said: "''What's quite clear is I have a very good relationship with Nicola Cortese, He agrees with my decision to stay and there's nothing more I can say about that right now."
Gus Poyet's Sunderland will bid for their fourth straight win in all competitions and are still hoping to add Estudiantes defender Santiago Vergini to their squad.
Fulham go to Arsenal with boss Rene Meulensteen tight-lipped over the Ravel Morrison controversy, while Morrison's current club West Ham are looking up in the wake of their hard-fought win at Cardiff last week.
Sam Allardyce's injury problems are beginning to ease with Andy Carroll, James Collins and Ricardo Vaz Te all likely to be in contention for Saturday's home clash with Newcastle.
Crystal Palace boss Tony Pulis is relishing the opportunity to renew acquaintances with his former club Stoke when they visit Selhurst Park.
Pulis said: "It is lovely to have Stoke coming down this weekend. I had a fantastic 10 years there and have wonderful memories of the club and it is very nice looking back on when we first went there."
Ole Gunnar Solskjaer faces a daunting first away trip as Cardiff boss as he takes his side to free-scoring Manchester City, while Aston Villa also have a difficult task to boost their ailing fortunes as they must face Liverpool at Anfield.
Swansea face Tottenham on Sunday while Roberto Martinez takes Everton to the Hawthorns on Monday night for Pepe Mel's first home game in charge of West Brom.