Out-of-favour strikers Aaron McLean and Nick Proschwitz were paired up front against Middlesbrough as Bruce made nine changes - partly due to rotation and partly to a sickness bug around the squad.
And they both responded by finding the net in a 2-0 win at the Riverside Stadium, McLean with an opportunistic strike in the 10th minute and Proschwitz with a powerful finish on the hour.
Bruce was happy to see the pair showcase their prowess in front of goal, but neither man has a long-term future at the KC Stadium and are available for transfer in January.
McLean, who last scored for Hull in October 2012, has just returned from a loan stint at Birmingham and could be first out of the door if they return with a permanent deal.
"There's a possibility they could both be gone before the fourth round because the transfer window is open," said Bruce.
"The thing is if you're a footballer and you're not playing every week you have a good right to knock down my door, and I would be exactly the same.
"If there is a solution for both that is good for them and good for us then we'll listen to it.
"But they both reminded us of what decent players they are and took their chances very well.
"I'm particularly pleased for Nick. He's had a disappointing time here but keeps reminding us that he can score a goal and I'm sure he'll be very pleased."
As for potential incomings, Bruce was more circumspect.
"We're just starting but as I've found in the past, it's always difficult in January and I'm sure it will be difficult for everybody in this window," he said.
While illness had laid low the likes of Alex Bruce, Robbie Brady and Robert Koren, Hull would probably have made significant alterations to their starting XI regardless.
Despite that, Tigers boss Bruce - a three-time FA Cup winner with Manchester United - does not agree with Aston Villa boss Paul Lambert that the competition is merely a distraction for top-flight teams.
"As Wigan proved last year, there is a competition there to be won," he said.
"We understand the Premier League is vitally important but the FA Cup is the FA Cup and believe me, if you get there it is one of the best days of your football life.
"Even though we made nine changes we've still got to be respectful and I think we are."
For Boro's Spanish boss Aitor Karanka, the result leaves his side focusing solely on the Championship.
His close relationship with Chelsea boss Jose Mourinho, who he worked as assistant to at Real Madrid, mean he has been tipped to raid the club's youth ranks for loan signings.
Nothing concrete has been confirmed yet, but he does expect Nigerian defender Kenneth Omeruo to sign soon.
"Jose and I are friends, so always since I have arrived here it has been talked about. I said to him 'listen, can I take Michael Essien'. Maybe not, but me and the club are working to take players," he said.
"I am happy (Omeruo) will come here to help us. I think that he will come until the end of the season."