Who will be the odd man out in Celtic defensive partnership?

Now that Celtic have completed the £7 million signing of Christopher Jullien, Hoops boss Neil Lennon has an intriguing dilemma on his hands. He currently has three first-pick centre-backs. Jullien, Kristoffer Ajer and Jozo Simunovic. However, as he is unlikely to switch to three at the back, only two can play at once...