Liverpool were 2-0 winners at Anfield last week thanks to goals from Daniel Sturridge and Roberto Firmino either side of half-time.
Liverpool deserved to go through over the two legs
Anthony Martial broke the deadlock from the penalty spot on Thursday night to offer Louis van Gaal’s side hope of an unlikely comeback.
However, Philippe Coutinho levelled before half-time and Klopp’s men progressed to the last eight thanks to a 3-1 aggregate win against United.
Speaking to ITV Sport following Liverpool’s 1-1 draw at Old Trafford, Hamann described the change in atmosphere in the Anfield camp since Klopp replaced Brendan Rodgers in October.
“There seems to be a lot of belief,” Hamann told ITV Sport.
“The mood in the whole camp has changed since Jurgen Klopp took over. He has got a lot of players playing a lot better.
“Liverpool deserved to go through over the two legs. Liverpool were by far the better side at Anfield last week.
“There wasn’t much in it in the second leg but a piece of brilliance from Philippe Coutinho finished the tie off.”
Liverpool will make the trip to Southampton in the Premier League at St Mary’s on Sunday afternoon.
The Reds are in eighth place in the Premier League table and seven points behind fourth-placed Manchester City in the race to secure a spot in next season’s Champions League.
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