Celtic conceded two goals against Partick Thistle last weekend and were reliant on James Forrest's hat-trick to see them through the cup tie.
Either way, whoever is selected to partner up at centre-half will have a real job on their hands to nullify the Zenit attack come Thursday evening.
Russian international forward Alesakdr Kokorin, 26, has enjoyed terrific form this season and has already surpassed his previous end-of-season goal tally of 13.
Nearing a century of career club goals, Kokorin has netted 18 times in 27 appearances this season, including an astounding eight in eight in European competition.
The Zenit frontman also has a history of scoring at Celtic Park, having netted the winner in a 1-0 triumph for Dynamo Moscow back in 2009 during a Champions League third qualifying round fixture against the Hoops aged only 18.
Nine years on, with over 200 games more experience and 50 Russia caps under his belt, Kokorin will be relishing a return to Glasgow and another chance to down the Scottish giants at Parkhead; the very arena at which he announced himself on the European stage.
Celtic's defence in general has been rather woeful this season, and the problem has only been exacerbated in Europe.
Across their six Champions League group games Rodgers' men conceded an embarrassing 18 goals, finishing with a goal difference of minus 13.
Celtic's defensive performance has not exactly been impressive domestically either, with the Hoops having conceded four goals in their last three games, which is simply not good enough given the quality of opposition they are up against.
On too many occasions there have been sloppy goals conceding and, if the likes of Connor Sammon are penetrating the Hoops' defence, it does not bode well when facing players of the calibre of Kokorin.