Celtic defender is below the level the club need right now.
Celtic secured a memorable Europa League win over RB Leipzig last night.
Odsonne Edouard scored a winner quickly after Jean-Kevin Augustin had cancelled out Kieran Tierney's first half strike.
Edouard's goal killed off Leipzig's revival and in the process saved teammate Mikael Lustig from becoming a scapegoat for what could have been a disappointing result.
The Swedish right-back was caught out of position for Leipzig's equaliser and his lack of concentration nearly cost his team.
With Tierney starring on the left, Lustig continues to be a weak link for Brendan Rodgers' side and it is a position which will end up costing them if Celtic qualify for the knockout stages and choose not to address it.
Lustig is 31 and his best days appear behind him.
Celtic don't need to send him packing in January, as right now he is the best option they have, but they should be looking to sign his replacement and use him as back up
Cristian Gamboa has failed to prove himself and remains second choice to the Swede.
This was a night where Celtic's top players stood up to be counted.
Lustig was exposed as one who was unable to rise to the challenge.