Meulensteen is determined to avoid a major FA Cup upset in the fourth-round tie at Bramall Lane as he attempts to turn around Fulham's fortunes this season.
The Cottagers are braced for a relegation dogfight over the second half of the season while Sheffield United are in a similar position in League One, but Meulensteen is aware the Blades represent a big threat on home turf.
"I warned the players they can't be complacent. I said that to them straight away (after the draw)," the Fulham head coach said.
"This will be a very difficult game. Sheffield United will try to chase everything and the crowd will get behind them.
"The key for us is to make sure we remain calm and focused and play away from that sort of pressure they throw at you.
"If you can maintain that, then the quality should see you through. But if you don't match their fighting spirit and enthusiasm you could be in for a tough, tough ride."
The Blades have climbed out of the relegation zone since Nigel Clough replaced David Weir as manager, but they are just one point above the bottom four having won one of their last six league games.
They delivered the shock of the third round with victory over Aston Villa, and Meulensteen believes there is a big difference in the way they approach the different competitions.
"It is like chalk and cheese. They are two completely different teams," he added. "You think you are looking at completely different players in the Villa game, but that is what motivation and the challenge does, so we are prepared for a difficult game."
Meulensteen is expected to hand a starting place to 21-year-old defender Dan Burn, who was recalled after loan spells with Yeovil and Birmingham and featured in both FA Cup third-round games against Norwich before starting the Premier League defeat to Arsenal last week.
"I had no hesitation about playing him against Arsenal," the Fulham boss said.
"I got bags of confidence from his two performances against Norwich and from what he was doing in training. He acquitted himself really well."
Sheffield United will be without the ineligible Billy Paynter so Chris Porter could return to the starting line-up to lead the line.
Tony McMahon has left for Blackpool in a loan deal that has seen Bob Harris move to Bramall Lane; he, along with fellow new recruits John Brayford and midfielder Stefan Scougall all go straight into the squad.