Nigel Clough has acknowledged the Blades will need to be at their best to prevail in Saturday's local derby with Chesterfield at the Proact Stadium.
The Spireites enter the game on home soil just a point and a place behind the Blades in Sky Bet League One, whilst they have the division's top scorer, Eoin Doyle, who has netted 12 times in all competitions to date, including hat-tricks in consecutive games against Scunthorpe and Preston North End last month amongst their ranks.
Looking ahead, the Blades boss remarked: "I am personally not surprised at all to see the likes of Chesterfield and Rochdale doing very well in League One, because as you often see teams with momentum from the previous season start well at a higher level.
"It was telling in the summer that they didn't go out and make wholesale changes to their squad. The manager has got confidence in what he already has at his disposal and he has just added and tweaked slightly.
"Like Rochdale, Chesterfield have plenty of confidence from winning promotion, but despite their excellent start I am sure Paul Cook will know that staying in this division remains their first priority.
"They have a great team spirit about them and they are clearly relishing life in League One, they see themselves as a match for anyone."
The Gaffer concluded by urging the Blades to stand up to the challenge that awaits in Derbyshire.
He added: "It will be a good atmosphere at the Proact, we just wish it was a 3pm kick-off. It is a big test for us and we have to make sure we match Chesterfield's desire in all areas of the pitch first and foremost because they will be keen to get one over us.
"Hopefully once the game settles down we will be able to play our football too and replicate certain aspects of the performance against Gillingham."