Celtic have had a very good start to their season so far and they will be looking to do well in the Champions League group stages later this month.
Although Brendan Rodgers has done well to add to his squad during the summer transfer window, his defence could certainly use another addition.
Since the August deadline has now passed, the Scottish champions could look into the free transfer market to improve their options. One such option is the Swiss international Reto Ziegler.
The defender was linked with a move to Celtic earlier this summer and he could be a useful option for the Hoops.
Celtic have one of the best young left backs in the world right now but Kieran Tierney might not be ready to start every game in the Champions League just yet. Ziegler is a lot more experienced option for the Northern Irishman. Also, he will allow Tierney to develop without being under too much pressure and without playing too many games.
Ziegler is currently a free agent and it will be interesting to see whether Celtic renew their interest in the player. The 31-year-old is not the best defender around, but he is certainly capable of making the grade in the Scottish league and being a backup in European games.