Chris Wilder says it was during the second-half of the game at Middlesbrough back in August that United realised they were able to compete in the upper echelons of the Championship.
Speaking ahead of Tuesday's return fixture, the Blades boss remarked: "When we first stepped into the division, we were looking at everything they had spent and the talent we were up against on that day.
"It seems a long time ago, but for 45 minutes we saw first hand what Championship football was about, we were on the back foot and they were comfortably leading."
Wilder added: "In the second-half we shook things up and the players went out there with the attitude that we were just at this level to make the numbers up.
"40 games later we're within touching distance of Middlesbrough, maybe that was a start for us and our attitude this season has been fantastic, we've shown all season we can and will compete."