Celtic's gutsy display against Barcelona this week raised Lennon's stock even higher, and McManus reckons his old team-mate will be eyeing a long-term contract.
He said: "I'd imagine that is something that is already being looked at. Lenny has managed to build a terrific young side and you only have to look at their displays in the Champions League this season so see how far they have come."
McManus watched his Lennon come within seconds of leading Celtic to a shock draw against Barca at the Nou Camp in the Champions League.
And he reckons it underlines the progress Celtic have made under Lennon's leadership.
But with a number of English Premier League clubs paying close attention, big Mick insists the job Lennon is doing won't have gone unnoticed in England and on the continent.
And he's adamant he's already proved he's worthy of a new deal.
He said: "If you look at how he has performed since taking over as manager, and how his team has performed, you can clearly see progress every year.
"Last season they won the title and performed pretty well in the Europa League and this season they have qualified for the Champions League with a couple of good results and then started the group campaign with a draw at home to Benfica and a win away at Spartak Moscow.
"To then go and perform as well as they did over in Barcelona is something Lenny and his players can be proud of and you can guarantee it hasn't gone unnoticed throughout Europe.
"It might make sense for the club to sit down with him and try and agree a longer contract.
"He is in charge of an exciting young team and if Celtic can keep moving forward under his management, it appears as though there are a lot of exciting times ahead."