Defeats to Rangers and AC Milan, and a 3-3 draw against Aberdeen last weekend, have piled on the pressure on Lennon and Celtic over the last week.
The Celtic boss came out fighting on Wednesday and went in to bat against suggestions that he should be sacked because of the Bhoys’ form.
McManus insisted that while Lennon is under pressure, the Celtic manager is deserving of all the criticism he has been receiving as the Scottish champions have been struggling since the start of the season.
He insists that Celtic scraped past average European sides to make it to the group stage of the Europa League and have dropped points against poor teams in Scotland as well.
McManus said on PLZ Soccer: “He is taking a lot of flak, but I think a lot of it has been deserved.
“I think Celtic have been playing really poorly. It is not just one week for me, it has been over the course of the start of the whole season.
“They have struggled in Europe as well – Riga, Sarajevo – they are two very average sides and they struggled past them.
“They have not been flying in the league, they have struggled past St. Mirren and Livingston.
“They are not firing in all cylinders and I think this week, it came to a head and their performances have caught up with them.”
Celtic are under pressure to get a result when they take on Lille in the Europa League later tonight in France.
