The Northern Irishman says he's leaving the door open over a return to Celtic.
Current boss Ronny Deila was already considered under pressure at Parkhead, but speculation over his future may just be cranked up a notch now after the Bhoys bowed out of the competition at the semi-final stage following a penalty-shootout defeat to their bitter Old Firm rivals at Hampden Park on Sunday.
The Northern Irishman, who also enjoyed a trophy-laden playing career at Celtic, is fondly remembered on the green half of Glasgow after winning three Scottish Premiership titles and two Scottish Cups during his four-year stint as manager, leaving in 2014.
He is currently out of work after being axed by Championship outfit Bolton Wanderers last month, and Lennon told the Daily Record that returning to Paradise would interest him.
“The door is always open to doing it from the dugout again – I made that clear when I left – but this time I’ll just be an interested observer although I won’t be impartial," he said, prior to Sunday's defeat.
Celtic were certainly far more of a European heavyweight under Lennon than they are under Deila, who has so far failed to qualify them for the Champions League group stages in two attempts. This season, they finished bottom of their Europa League group, comprising Ajax, Fenerbahce and Molde, losing three and drawing three of their six games.
Under Lennon, on the other hand, Celtic did manage Champions League qualification and secured a stunning 2-1 win over Barcelona in 2012 for arguably the flagship win under the 44-year-old, reaching the last 16 that year.