Dejan Lovren was dropped last weekend in favour of Kolo Toure because of the Ivorian's committment, Liverpool manager Brendan Rodgers said.
Rodgers chose to start the veteran Toure instead of Lovren, a £20 million summer signing, in the defeat against Arsenal on Saturday, and the manager defended the decision.
"The thing with Kolo is he gives me everything every single day so I know what I am going to get with him," Rodgers told national newspapers.
"Dejan was someone who was out over the international break, now he is fighting well and looking strong. He will be in contention for the cup game for sure."
Lovren has a solid chance of being selected on Wendesday against Liverpool in the FA Cup quarterfinal replay because both Martin Skrtel and Emre Can are suspended.
The Croatian is not the only new addition who has struggled to live up to expectations this season, with Mario Balotelli, Adam Lallana, Alberto Moreno and Lazar Markovic all inconsistent.
Rodgers attributed their moderate beginnings at Liverpool to a necessary period of adjustment.
"You bring players in with all the intentions of them doing well," Rodgers said. "What you cannot vouch for is when you come into a club of this size how long that adaptation process is going to take.
"You've seen that over many years at this club. You can be a very good player and not hit it off for some reason or it just takes time, like Lucas Leiva. These players need time and you don't get that in modern football.
"In the transfer market there are always going to be some players that work for you and some that don't, and it's about getting the balance shifted towards the positive.
"We had a big influx of players last summer so it was always going to be difficult for them all to hit it off straight away but I think you can see the progress that has been made."
Liverpool's chances of qualifying for the Champions League are slim after two straight defeats, but even seven points back with seven to play, Rodgers is not giving up hope.
"It is certainly not the mindset or attitude we want here at the club," he said. "We have to fight to get in there, and whatever the barriers are in front of us, whether it is finance, whatever of other clubs, we have to do everything we can to break that barrier.
"We recovered the season in that mid-section and now we have to fight until the very end and look to keep progressing as much as we can."