Gary Speed is expecting a tough day at the office when third plays fourth at Bramall Lane on Saturday, but the midfielder tells Blades fans there is more to come from Kevin Blackwell's men.
Speed has impressed in his last two appearances after recovering from a calf injury and is pleased that United have laid down some solid foundations to date.
But he appreciates the meeting with the Royals will be a real yardstick of United's progress so far:
"They are on a good run at the moment and have been picking up results, but so have we. With that in mind, it should be an exciting top of the table clash.
"It is a very important game against one of our rivals and winning games like this can help us achieve our main goal for this season, which is promotion - but at this stage of the season it isn't a matter of life or death.
"Because of the nature of this division, anyone can beat anyone on the day, so although this game in important it is no more or less so than a match against a team lower down the table."
After extending their unbeaten record to five matches at Barnsley last week the Blades moved up to fourth, but the former Wales skipper insists there is more to come from the team in all areas:
"We want to be unbeatable and we train hard to try and achieve that, but realistically it doesn't happen for long. We have got a solid team, with an excellent team spirit and we work really hard for each other.
"Saying that, we can improve in all areas, Paddy has been excellent but we can't keep relying on him to make great saves so we need to give him a hand, whilst at the other end we need to be sharper and we must get goals from everyone - not just James Beattie!"