The Hoops boss has admitted he was impressed by his side's strong performance at Celtic Park, but says playing in Portugal will be a tougher proposition
An outstanding performance from Scott Brown and a series of Kris Commons chances failed to give the Old Firm club the breakthrough they desired.
Lennon is confident that Celtic can grow from their opening game performance and forget their 2-1 away defeat to St Johnstone in their last SPL outing, but admits playing away from home will be a tough proposition.
"I am pleased," he told Sky Sports. "It was a tough game against a quality side. I thought we coped more than admirably.
"We had more of a cutting edge before half-time, but it improves as we go on. It's going to be difficult away, the away leg is always a different beast."
Lennon is confident Celtic can compete for a place in the next round of this season's Champions League, despite being drawn in the same group as Spanish giants Barcelona.
He added: "Qualifying will be very difficult from this group, but it's always hard in Champions League football."
Midfielder Brown was delighted with his side's performance in their first Champions League appearance in four years, admitting that he thought Celtic were the better team on the night.
"I thought we played really well, we battled well and played good football as well," he stated. "Overall, I thought we were the better team."