Ibrahima Konate rued the errors made by Liverpool that contributed to Sunday's 3-2 defeat at Manchester United in the Premier League.
The Reds' second-half recovery was undone by the winning goal from Kobbie Mainoo in the 77th minute at Old Trafford.
Trailing 2-0 at half-time, the visitors had restored parity shortly after the break with finishes from Dominik Szoboszlai and Cody Gakpo.
"For sure, it's a big disappointment because I think we concede two goals that we must not concede when we start the game," Konate told Liverpoolfc.com. "[In] the second half we came back with a great mentality to [go] 2-2.
"And in other moments we can hurt them but we concede a goal and that's why it's very sad for us, because we didn't start the game very well but the second half we started very well.
"I think it was a big opportunity to take three points and we didn't get anything."
United established their two-goal lead within the opening quarter of an hour, when Benjamin Sesko followed up an early opener from Matheus Cunha.
Szoboszlai scored two minutes into the second period to halve Liverpool's deficit and they were then back level courtesy of Gakpo's 50th strike for the club.
On what was said in the dressing room at the interval, Konate shared: "It was just about the mentality. In the first half we lost many challenges on the pitch. When it was 50-50, most of them Manchester [United] won them on the pitch.
"But in the second half we just had to change it and change the mentality. This is what we have done and that's why we scored two good goals with our pressing, with our aggressiveness. But we needed a little bit more."
The defender continued: "When you were 2-0 down and you come back to 2-2, for sure you have the energy, you have the desire to come back and to win this game.
"After, we concede the 3-2 and we have to work on it, we have to understand why we concede this goal as well and keep going until the end of the season to be in a good position for the Champions League."
Read our match report here
With three games remaining in the campaign, the Reds are looking to confirm a place in the Champions League for next season.
Chelsea arrive at Anfield this coming Saturday for a lunchtime showdown, ahead of meetings with Aston Villa and Brentford.
"It's three big games and we know all of them try to be qualified for Europe," Konate finished. "We just have to be ready for the next game against Chelsea next Saturday."
