Liverpool manager Jurgen Klopp has confirmed Roberto Firmino suffered a small injury in training, which ruled the forward out of the Carabao Cup tie against Manchester City.
Firmino had been expected to be involved for Klopp's side in the fourth round tie, after playing both warm-up matches during the World Cup break.
The forward had been left out of Brazil's squad for the tournament in Qatar.
Klopp confirmed to Sky Sports that Firmino had suffered a small injury in training on Tuesday, which prevented him from being involved in the fourth round tie.
'We play mainly with the players who could do all the sessions now and had a break – apart from Bobby, who unfortunately got injured two days ago in training,' Klopp said.
'Not a big one but big enough for this period. That's why Darwin is now starting. He could've started anyway but Darwin is starting now.
'Apart from that, all the others could've played. I'm pretty sure Hendo could've played, Fabinho could've played, Ali could've played but that's clear with the competition.
'Just Virgil only arrived yesterday. We gave him two days more because he's really our all-time player.
'He played all the games for us, played all the games for Holland, so we thought it makes sense to give him two more days because obviously a really important part of the season is ahead of us and we are really desperate to make sure we do it the right way.'
Firmino's injury is an additional blow, with the Reds already without Luis Diaz and Diogo Jota.
Liverpool will hope to have Firmino return to fitness for the busy upcoming schedule, with Klopp's side set to face Aston Villa on Boxing Day on their Premier League return.