Jamie Carragher believes that Liverpool squandered a chance to solidify their superiority over Manchester United in the summer.

Sir Alex Ferguson's retirement at Old Trafford preceded United's lowest ever finish of seventh in the Premier League era, while Brendan Rodgers's Reds mounted their most credible title challenge in 24 years as they finished runners-up to Manchester City on the final day.

However, Carragher thinks that his former side's summer transfer dealings were poor and the ex-Anfield defender has admitted that United have responded well to last season's disappointment.

He told the Daily Mail: "When Ferguson retired, a door opened for Liverpool. He was an empire on his own, one of the biggest influences on football this country has seen but, suddenly, his departure transformed things. There was a glimmer of light to exploit.

"Yet here we are on December 13, exactly seven months after the last campaign ended, and United are back on the front foot, third in the table. They are an average side, compared to Ferguson's teams of the past, but being in transition has not hindered their ambitions.

"In adding Angel di Maria and Luke Shaw, United bought the better players. Liverpool may have spent more than £100m but where has it left them? And when will they be able to lavish such a figure again? Looking at them now, you feel they need another £100m spending just to improve. [United] need working on before they reach a title-winning level once more but they remain on their perch they claimed in May 2011. Liverpool have let them off the hook."

Liverpool travel to United on Sunday afternoon, seven points behind them in the Premier League table.