Everyone believes in themselves and we're confident that we can go far in the competition.Caolan Boyd-Munce
Blues head into tonight's encounter under the floodlights in an excellent run of form, having been beaten just once in their previous 11 matches.
In fact, the last time they lost was against the Blades in late November in the league.
"Everyone is buzzing about this game since we got through the last round," said the influential Northern Ireland Under-19 international.
"Training has just been geared towards playing at St. Andrew's because it's such a big occasion for everybody.
"In the last round away at Bristol City it was the first time playing in a stadium under the lights for a lot of the players and some of them were a bit nervy, although there were bits of quality.
"Because we've already experienced it, we should be a lot more at ease and relaxed.
"When we played Sheffield United in the league it was a bit of a mismatch because we had a lot of players missing through injuries or with the Under-23s, but now we've got almost the full squad available.
"But our start is massively important, which means getting Sheffield on the backfoot straightaway and sticking to our gameplan.
"We need to get out of the blocks quickly and press and move the ball quickly."
Blues reached this stage of the competition with a 2-1 away victory at Bristol City, courtesy of goals from Tommy Anderson and Nick Okoro.
Meanwhile, Sheffield United dispatched Burton Albion 2-0 at Bramall Lane, thanks to a second-half brace from Jordan Doherty.
The winners of tonight's tie will face either Aston Villa or Bury away in the fifth round.
And whilst Boyd-Munce says that in itself is a massive incentive to progress, he also says this fixture is chance for players to impress on an individual level.
"The possibility of playing Villa in the fifth round is a brilliant draw, although we are trying not to think about it.
"But we just have to concentrate on trying to get through this one first.
"Everyone believes in themselves and we're confident that we can go far in the competition.
"As a player, it's an excellent shop window for many of the players with pro-contracts coming up and the chance to further their own careers."
Admission to tonight's game is just £4 for adults and £2 concessions.
If you can't make it to St. Andrew’s, you can watch the game live on BluesTV. To sign up to BluesTV, click here.