Chris Wilder was disappointed with his team's performance in the 0-0 draw at Mansfield Town.
After three pre-season victories, a draw was all his side could muster against David Flitcroft's Stags.
Wilder commented afterwards: "I don't think we were competitive, the opposition were outstanding and deserved to win. It cements my belief, 100 per cent, that you need to compete.
"The opposition were far better, with and without the ball. Maybe the players have strolled into Mansfield thinking we were Championship players - maybe they need reminders about what we need to do and what we need to do better.
"Mansfield will go well this season, but we were second best all over the park. We have done well in pre-season but I don't like it when we get outbattled and outmuscled in any game."