Liverpool managed to solve a major issue that was preventing them from challenging for titles by signing Brazilian goalkeeper Alisson from Roma.
Jurgen Klopp now has a world-class stopper in his ranks, but there are still question marks over the back line, and in particular who the best centre-back pairing is.
Virgil van Dijk automatically gets a spot as he has bred confidence in the defence since his January arrival from Southampton.
Towards the end of the season, Dejan Lovren partnered the Dutchman, but with the World Cup finalist on the sidelines with injury, Klopp has to rejig his team.
Prior to an injury, Joel Matip was first choice, but he has since suffered numerous fitness problems.
The defender has not played since March, and a thigh problem in pre-season put him on the treatment table for another spell.
Last Sunday, Joe Gomez started alongside Van Dijk in Liverpool’s 4-0 victory over West Ham United on the opening weekend of the Premier League season.
On Wednesday, the Liverpool Echo reported that Matip came through a 60-minute practice match at Melwood, which suggests that he could be in contention to face Palace.
Some Liverpool fans have been deliberating over centre-back pairings on Reddit after the news emerged.