Liverpool captain Jordan Henderson will be out for three weeks with a hamstring injury sustained in their 1-0 midweek Champions League defeat by Atletico Madrid, manager Juergen Klopp said on Friday.
The injury rules the influential midfielder out of Monday's Premier League home game against relegation-threatened West Ham United, a match in which the runaway league leaders will be desperate "to put things right", the German added.
"It's not that bad, but he will be out I think for three weeks or so, which is not cool but how we see it is we were still lucky and that's it," Klopp told a news conference.
Liverpool's Champions League last-16 first leg defeat on Tuesday was just their third loss of the season in all competitions and their first since their youth side was beaten by Aston Villa in the League Cup in December.
"It's a little bit strange," Klopp said of the loss in Spain. "Yes, we lost the game and there's absolutely no positive in it.
"But it's important... that it felt like a defeat. It felt after the game like a defeat, it felt the next morning like a defeat. But the thing is... to get the other feeling back... the feeling of how a win feels.
"We've won a few games and now we've lost it and the difference is massive. Much more than three points. It's really from sunshine to hardest rain and that's how it should be.
"If you really want to be successful... like we could have been in that game, then it has to feel really bad and that's how it felt. So yes, we want to put things right even when it's a different competition."
West Ham, who were beaten 2-0 by second-placed Manchester City in their last league outing, would come to Anfield and "defend with all they have", he added.
"With all the brilliance that Man City have... (West Ham) weren't outplayed like you would expect when City is on the pitch," Klopp said.
"They... didn't have a lot of possession obviously so I wouldn't expect that they go for much more possession against us but... I think they took some positives out of that game and they will try it again and we have to be ready.
"I expect a really tough match, 100%."