New defender James Wilson says Tuesday's reversal at Halifax Town indicates United's pre-season preparations are still very much a working in progress.
United, who had previously beaten Stocksbridge Park Steels and a Murcia XI whilst in La Manga, slipped to a disappointing loss in West Yorkshire.
And reflecting on the 2-0 loss at the Shay Stadium, the centre-half, who penned a two-year deal at Bramall Lane earlier this month, remarked: "We are going to come up against teams who play that way in League One.
"And we've got to deal with it better than that. Yes, it's pre-season but we need to work on things pretty quickly. That will happen though. We'll work hard to correct and make them right."
Wilson added: "These games are useful exercises and we have to take them seriously.
"We played some decent football at Halifax but not for long enough periods. That is something we are going to have to put right on Saturday as we step things up against Grimsby."