The burgeoning partnership between Shane Long and Nikica Jelavic was at the forefront of Hull's 4-0 Premier League trouncing of Cardiff City on Saturday.
However, having represented their previous clubs, West Brom and Everton respectively, in the competition prior to joining Steve Bruce's side in January, the duo are ineligible for Monday's fifth round replay against Brighton.
That is sure to be a blow for Bruce, who waxed lyrical about his most recent recruits after the win at the Cardiff City Stadium.
"When you are not playing very well, if you've got two like we have then you are a threat," the manager said.
"The link-up play was there for all to see. The two of them have a great appetite for the game and work ethic.
"With the pace of Long and the physical presence Jelavic gives you, with a turn of pace too, they are a handful for any defence."
But the visiting Championship side will still have their hands full at the KC Stadium, with Yannick Sagbo and Sone Aluko set to lead the line for Hull.
It was Sagbo's last-ditch leveller that earned a 1-1 draw at the Amex Stadium to set up the replay after Leonardo Ulloa had put Brighton in front.
Should he get the nod, Sagbo is likely to be one of several changes for what will be Hull's second game in three days – something manager Bruce has previously bemoaned.
"I find that ridiculous, I have to tell you," he said. "Surely we could play on the same night as the Champions League, you would have thought.
"I think it is a UEFA rule, which reads nobody plays on the same night as the Champions League. We'll have to take it as it is and deal with it as it comes."
Brighton manager Oscar Garcia, who concurred with his opposite number's view on the schedule, is also likely to make alterations having made seven for the initial tie.
His play-off chasing side enter the game desperate to get back on track following a disappointing 2-1 home loss to Wigan Athletic on Saturday.
The winners will host Bruce's former club Sunderland, managed by ex-Brighton boss Gus Poyet.
