Neill Collins has praised the Blades for the early season efforts in League One, but insists there is still plenty of room for improvement.
Although United arguably deserved more than five points from the first three matches, the Scottish defender says there is plenty of cause for optimism and he expects the team to improve as the season progresses:
"We have only conceded two goals in three league games to date, but that has included two draws so it is a positive and a negative, in that respect.
"Clean sheets are what we are aiming for but the defence is a new team within a team and we can take plenty of heart from our early season form."
Speaking of the competition for places within United's backline, Collins added: "We have good experience in defensive areas. We all knew Matt Hill from last season and along with Marcus Williams they have competition for a starting berth on the left.
"Tony McMahon has great experience for his age, he has done well in the games he has played and no doubt Darryl Westlake will be pushing him when he gets over his injury.
"It takes time for a defence to gel, but I am sure we will get better and better."