Victory over Manchester City would be one of the 'best ever results' says Manchester United boss Alex Ferguson

Manchester United manager concerned by leaky defence ahead of this Sunday's derby

Manchester United manager Alex Ferguson (GETTY IMAGES)

Sir Alex Ferguson says victory for Manchester United over rivals Manchester City this weekend would rank among the 'best results ever' for the club.

United make the short trip across Manchester this weekend, leading their noisy neighbours by three points in the Premier League. Yet despite topping the table, United have not been wholly convincing this season, certainly in terms of defence.

Earlier this week Ferguson likened some of the antics across United's back line to a cartoon and as such believes victory at the Etihad Stadium would be hugely significant.

"If we win [on Sunday] it will be one of our best ever results," Ferguson told MUTV.

"They are a really good, powerful team with massive players.

"It won't be easy and if we defend like we did at Reading we'll be in trouble.

"The important thing for us is to take lessons from the mistakes we're making and do something about it. We need to find a solution."

In Ferguson's programme notes for last night's 1-0 Champions League defeat to Cluj, the Scot predicted a tight match between the two sides that look certain to duke out the title between them.

Although Ferguson is wary of discounting other title rivals entirely.

"At this time in the season you can't really say it's a two-horse race," he said.

"If you think back we were 12 points behind Chelsea at one point and when Arsenal beat us in the league in 1998 we were 11 points clear."