The Hoops crashed out of the Europa League with to games left to play after throwing away a one-goal lead in the Czech capital and succumbing to a second consecutive continental defeat by that heavy scoreline.
The result came in the aftermath of a protest from well-known supporters’ group The Green Brigade, who made headlines on Wednesday by holding up a large banner outside Parkhead that read: “Save the ten – Time to go Neil”.
Calls for Lennon’s sacking were initially dismissed by pundits, with Sky Sports’ Andy Walker and former Celtic hitman Chris Sutton both rallying around the under-fire manager – even with his side 11 points adrift of Rangers at the top of the Scottish Premiership table.
But following the Bhoys’ latest setback, Stewart is less optimistic about Lennon’s prospects.
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Speaking on BBC Sportsound, the pundit said: “There is a complete lack of defensive awareness. The goals that Celtic are losing now would never have happened under Brendan Rodgers, it’s as simple as that.
"The defensive cohesion as a unit when in possession to make sure that in transition teams couldn’t do what they’re doing to Celtic now, was in a different stratosphere to what is happening now.
"I heard on commentary there, is this the crumbling of an empire? It certainly looks that way.
"It’s not easy to say, but it feels as if that could be the endgame there for Neil Lennon at Celtic. I don’t see how it turns round from here.
"Two 4-1 defeats, successive defeats in Europe, and to have flitted between a back three and a back four, changed personnel but nothing’s really changing – it’s as if the message is not being listened to now.
"Some can say it’s unfortunate, others will say it’s the nature of the beast and that’s the industry they work in, but something’s not right, and something’s not working.
"There’s been so many different alternatives tried, and it just feels to me as if that could be the end.”