Celtic made a limp exit from the Europa League, losing 4-0 to Utrecht despite taking a two-goal lead to Holland and failing to qualify for the group stages of the tournament.
Now Lennon is demanding a response from his players in domestic competition when they resume their championship bid with a trip to Motherwell on Sunday.
Lennon admitted his players now have "bruised egos" after their European battering, but wants them straight back in the ring and throwing punches at Fir Park.
He said: "We've still got three trophies to challenge and compete for.
"The priority has always been the league. We have to make a real challenge for the league now.
"The defeat on Thursday night we can use as an incentive and a reminder, too, if at any point the players think they're better than they are.
"It starts on Sunday for us. We'll make the players aware of what's required. We'll go to Motherwell and take it from there.
"I still trust the players. The domestic performances have been pretty good, we've had setbacks before and they've responded in the right way so I'm looking for a similar response."
Lennon has compared the Utrecht result to the setback he received when in caretaker charge of Celtic as his team tumbled out of the Active Nation Scottish Cup at the semi-final stage to Irn-Bru First Division side Ross County.
In the aftermath of that Hampden defeat, Lennon was openly critical of his players in public, but is playing it differently this time.
He added: "I won't make a kneejerk reaction. I did after Ross County because it was endemic of the season that had gone on before. This is a new team. I can't have too many opinions on the players yet.
"I've got a decent squad that can be in contention domestically.
"An overall collection of things went wrong against Utrecht. It's the manner we're conceding, it's poor, and the reaction to letting them in was poor. The overall performance was far from what I was looking for.
"It probably hurt more than Ross County because it's more my team now. It's players I've brought in so it does hurt more."