Brendan Rodgers said he was "disappointed" by Liverpool's 3-0 loss to West Ham at Anfield and insisted that his side have to defend better.
A goal from Manuel Lanzini inside five minutes set the tone and Mark Noble doubled the lead before the half. Liverpool then had Philippe Coutinho sent off for a second yellow card, before Diafra Sakho put the seal on the win to end their unbeaten start to the campaign.
"The first goal is a cheap goal and that gave them a motivation and fight," Rodgers told BBC Sport. "The second was a mistake, which can happen.
"We started brightly and then had Coutinho sent off. I didn't think that was a sending off and neither was the one for Noble as well.
"We didn't defend moments well at all. We need to be much better than that. That opportunity to work the goalkeeper didn't happen. We are disappointed but we'll reflect on it and come back and look to win our next game."
Rodgers also bemoaned sloppy goals for their first defeat of the season after three successive clean sheets.
"We were disappointing today. We went in with confidence high but when you give away a goal so early it gave West Ham a boost,'' he said. "I think it was the overall performance with and without the ball. We disappointed right from the off.
"Once we conceded that early goal we just couldn't get back into the game. The moral and confidence has been really high and they have been developing and improving. A lot of it today was self-inflicted. We gave poor goals away and that was the biggest disappointment.''
Rodgers also felt Coutinho was unlucky with his red card, which means he will miss the trip to Old Trafford when the Premier League resumes after the international break.
"I thought both sending-offs were very harsh,'' he added. "He must have real good ears Kevin if he could hear (dissent for Coutinho's first caution) because there was some distance . If he has been booked for that I'll be surprised but it looked like that when I saw the replay."
Meanwhile, having both beaten and lost to opponents they were not expected to, West Ham United defender Winston Reid has called for greater consistency to make the season a success.
"We're choosing to get our victories at difficult places this year," he said.
"We need to show up for the lesser sides as well. We can't just play well against the good teams or it will be a long season.
"It is still early days. Just because we went to Liverpool and won, it doesn't mean we are going to be a top team.
"In the easier games we need to show up and see the same desire and commitment."
Reid signed a new contract in March after much speculation about his future and the centre-back, who did a superb job keeping £32.5 million striker Christian Benteke quiet, is optimistic about the future.
"Slaven is a good manager. He does things in his own way. He is getting his ideas across really well," he added.
"I am happy and settled here, otherwise I wouldn't have signed.
"We've had a new start with a new manager, and the place has been freshened up a little bit, so I am looking forward to it."