Jurgen Klopp lamented the two first-half errors Liverpool made that led to Saturday's 2-1 defeat at the hands of Manchester United.
Liverpool's seven-match unbeaten run was ended at Old Trafford by two goals from Marcus Rashford within the opening 24 minutes.
Romelu Lukaku beat Dejan Lovren in the air to the build-up to both of Rashford's goals, with Klopp subsequently unhappy about how his side afforded too much space to United's forwards.
"I have no explanation for that because it's clear, really clear, that they played a lot of long balls and Lukaku is on the pitch then it's around him," the Liverpool manager told Sky Sports. "We were not there.
"It happens in football. If you don't make mistakes then the other team cannot score. I said the second ball was the one thing, but I think it was the first from Rashford when he cuts back, we need to be there, 100 percent.
"We [were] then chasing the game. In these two decisive moments, we were not good. We have to defend these situations better.
"We have to protect these situations better. We were not around. You can always lose a header and challenge with Lukaku, of course. There's a gap in behind and we need to close that. In these situations, we were not there. So they could score the two goals and that made the game not easy."
Liverpool were afforded a lifeline when Eric Bailly scored an own goal in the 66th minute, but were unable to go on and find an equaliser.
However, Klopp, who feels Liverpool did enough in the second half to warrant a draw, believes Liverpool's should have had a penalty when, he felt, substitute Marouane Fellaini brought down Sadio Mane nine minutes from time.
"I thought in the second half we chased the game, which is what you have to do against a team like Manchester," he said.
"[We] had more chances and I think it was a clear penalty with Fellaini on Sadio. In a situation like this, you need the right decisions, if you want -- we didn't get them.
"In a lot of other moments we were good, we fought back, we played with big hearts, we played football.
"We had everything in the box, but not the clear chances. I think the clearest was [when] Roberto back-heeled to Sadio. If there's no foul, he shoots. He's free in the box. It's a clear foul then.
"They scored two and we scored one, so they deserved the three points. But I think at least one point would have been absolutely fair for us, but we have to take that as well."
The loss, which was just Liverpool's fourth of the league campaign, means United open up a five-point over Klopp's side in the battle for the Premier League's runners-up spot.
"It was 2-0 early and a lot of things can happen in a football game," Klopp said. "We reacted -- that's our duty, by the way. We did that.
"What we said before the game is still true after the game, it's all about the result -- and we lost."