Jordan Henderson will be out for around three weeks with a hamstring injury suffered during Liverpool’s Champions League defeat at Atlético Madrid, according to Jürgen Klopp.

The second leg of that tie comes in just under three weeks, on Wednesday 11 March. Henderson appears certain to miss four other matches: the FA Cup tie at Chelsea and three Premier League fixtures, starting with Monday’s at home to West Ham and then games at Watford and at home to Bournemouth.

A three-week absence would allow the captain to return for the derby at Everton on Monday 16 March.

“It could have been worse,” Klopp said. “We know there are a lot of different hamstring injuries in the Premier League at the moment, with Harry Kane and so on, but it’s not that bad. He will be out for about three weeks, which is not cool. But how we see it, we were still lucky. Hendo is exceptionally important, not just football-wise but for other reasons as well.”

The Liverpool manager has also warned his players – and the home support – against complacency against West Ham, adding that the relegation-threatened Hammers showed plenty of grit against Manchester City.

“They fought really hard [against City] and defended the box with all they had … they were not outplayed,” Klopp said. They took some positives out of the game and they will try it again so we have to be ready for that.”

“It’s a night match and we need a really good atmosphere. Not this perception that it will be 1-0 after seven minutes, 2-0 after 24 minutes and it will be easy. West Ham need to fight. They don’t have time to waste points. I expect a really tough match.”

Sadio Mané is expected to start the match after being withdrawn at half-time in Madrid after being booked. Klopp admitted the forward was “surprised” by the decision to substitute him, with the forward on a yellow card.

“I spoke to him (on Friday) morning, I asked was he surprised and he said ‘yes’,” Klopp said. “We needed him physical, having contact with opponents. It’s part of the game, I don’t like it too much … eight players around the referee.

“I didn’t believe we could complete the game with 11 [players], with him on the pitch. But now he’s completely fine, he’s rested which is good as well.”