Celtic boss Neil Lennon was looking for a strong reaction from his side at the San Siro as they aimed to bounce back from a shock Scottish League Cup exit at the hands of Ross County at the weekend.
And Celtic started strongly in Italy, with goals from Tom Rogic and Odsonne Edouard within the first 14 minutes putting the visitors in control.
However, AC Milan went in at the break level thanks to a free-kick from Hakan Calhanoglu and a Samu Castillejo goal.
The Italians built on the goals and scored again in the second half through Jens Petter Hauge and Brahim Diaz, completing the comeback and handing Celtic a 4-2 loss.
Former Hibernian attacker McManus believes Celtic performed well enough in Italy, but stressed they continue to be soft defensively.
“Celtic have done ok here against a really good Milan side”, McManus wrote on Twitter.
“Loads of spirit and kept going to end.
“But defensively they are so soft it’s embarrassing. No desire to keep clean sheets/defend the six-yard box. Throwing bodies at shots etc.
“No leaders. Goalkeeper yet to make a save of note either.”
Lennon will hope his men take the positives from their encounter with AC Milan as they prepare to return to domestic duty this weekend against St Johnstone at Celtic Park.
