Manchester United striker Wayne Rooney believes the players still have plenty of room for improvement, despite sitting top of the Premier League table with a third of the season gone.
The Red Devils lead local rivals Manchester City by a point, despite having lost three times already this campaign, whilst the reigning champions remain undefeated.
But, Rooney has urged his team-mates to up their game, following a series of under-par performances, which has seen Sir Alex Ferguson's side ship 18 goals in 2012/13.
"Clean sheets are the foundation we hope for, we know we have players who can score goals and win us games," said the 27-year-old. "If we can get a clean sheet, then I'm sure we can get them at the other end and win games.
"As a team, we've played some good stuff at times but we've also ground results out as well. To lose three games this early is something we need to put right.
"We're lucky that we've won all the other games and not drawn any. It means we're still in a good position in the league. So we need to make sure we are full focused now and try to kick on, try to go on a good run."
United's leaky back-line has seen them concede first in 12 of their last 20 matches, including in Saturday's 3-1 victory over basement boys Queens Park Rangers at Old Trafford.
It's a trend that Rooney is keen to end, by addressing the team's form and tightening up in defence with a renewed emphasis placed on keeping clean sheets.
"I don't know why it is but it's happening too many times," he continued. "We need to just go out now and try to get the early goal. As soon as we get a goal, the team settles down and the game settles.
"We tend to take control of the game. But more often than not we've conceded first and made it hard for ourselves to try to get back in the game then go on and win it."
Next up for Manchester United is the visit of West Ham, who travel to Old Trafford off the back of a 3-1 defeat against Tottenham Hotspur, having won just one of their last six games.