In Dedryck Boyata and Filip Benkovic, Celtic have found a strong central defensive partnership.
Some may argue that Boyata and Benkovic is the best centre-back pairing that Celtic have had since the days of Virgil Van Dijk and Jason Denayer.
But by the start of next season, both players might have left Celtic Park.
Boyata has been strongly linked with an exit and considering his contract is set to expire next summer, Celtic need to cash in this January to avoid losing him on a free.
Brendan Rodgers has confirmed that it is likely that the Belgium international will leave in January.
This already leaves a void at the back for Celtic with Benkovic needing a new central defensive colleague.
But it could get worse in the summer with Benkovic’s loan deal set to expire.
The towering Croatian defender is only on loan from Leicester City until the end of the season.
And considering his impressive form, and the fact that Harry Maguire could leave, Leicester are likely to keep him next term.
Celtic fans will want the 21-year-old on a permanent basis but that is unlikely.
Kristoffer Ajer will step up as one of the two new centre-backs and the Norwegian defender is more than capable of filling that void.
But a partnership of Ajer and one of Jozo Simunovic and Jack Hendry is less convincing than Boyata and Benkovic.