Liverpool boss Jurgen Klopp admitted his side lost concentration as they twice let slip the lead to draw 2-2 with Sunderland at the Stadium of Light on Monday.
Daniel Sturridge gave the visitors a 19th-minute lead before Jermain Defoe equalised from the spot six minutes later after Didier Ndong had been brought down by Ragnar Klavan.
Sadio Mane then restored their advantage on 72 minutes, but the Senegal international conceded a penalty when he handled in the area six minutes from time and Defoe converted from 12 yards out again to earn a share of the spoils for the Black Cats.
Klopp felt the fact that the Reds had played two games in the space of 48 hours may have had a hand in their lapses at the back, as the German experienced his first taste of festive football in England.
"For me, it's completely difficult to assume [anything about] the game, because I have no experience – in situations like this, I have no idea what I could have expected from the performance side," he said after the match.
"I thought we started really well and then we lost concentration. That's not usual for us. But, of course, it happened before.
"It could be because of the fixtures, I'm not sure. Sunderland came a little bit into the game. It was clear at home it was difficult against Sunderland. [They have] a good transition game, especially with Defoe and [Fabio] Borini.
"The goal, the penalty, was after a throw-in. Second half, we again dominated the game. Usually I would say we could have done better, but I don't know exactly if we could have done better because I was not in the boots.
"We scored the second goal – felt good, felt deserved. Then, I would say no foul, but a free-kick [was given]. I saw it again – no contact. Then handball, 2-2.
"That's how it is. I must be honest, it doesn't feel good. It's not because of the point. It's because of two penalties in the game. That was harsh and really hard to accept. But obviously I have to accept it, so I will."