Liverpool coach Jurgen Klopp says his side did not play at the level required to beat Manchester United as the Reds suffered a 3-2 defeat in the FA Cup fourth round on Sunday.
The visitors led early on thanks to Mohamed Salah's opener, with the Egyptian's second of the game bringing the Reds level after Mason Greenwood and Marcus Rashford had put the Red Devils ahead.
Bruno Fernandes settled the tie after 78 minutes with an excellent free-kick that beat Liverpool goalkeeper Alisson at the far post.
Klopp was happy with many aspects of his team's performance but feels they made too many mistakes in key moments.
"There was a lot of good things and some mistakes around the goals. If you want to win here you have to be absolutely top and we were not," he told BBC Sport.
"For the first goal we had no protection, we wanted it too much. Things like this should not happen but they can happen. We had too many players in a receiving position.
"We can take things out of this game, we try to learn from every game."
Salah's double takes his goal tally up to 19 in 28 appearances in all competitions.
"It's good for Mo Salah, good for the confidence," Klopp said of the Egypt international's double.
"It was a tough game. We want it hard but tonight it was not enough. If you win a game there are negatives if you lose a game too but I saw the boys really, really wanted it.
"We had problems on the counter-attack, it was intense, but there were positives."
He later told reporters at a press conference: "We scored two goals, we had other situations where we could have scored as well, we had other situations where we created really well against a deep defending block, so there were a lot of good things."
The reigning champions have won just one of their last seven matches - a 4-1 win against Aston Villa in the previous round of the FA Cup - and will be looking to get back in form on Thursday when they face Tottenham in the Premier League.
The German coach hopes his side can use what they learned from Sunday's defeat in the clash with Jose Mourinho's men.
"I saw a lot of steps in the right direction, that's good preparation for the Tottenham game, with their counter-attacking threat, so we know exactly what we have to do," he said.