Celtic have one foot in the Europa League group stage after their 1-1 draw with Suduva in Lithuania on Thursday.
However, city rivals, Rangers manager Steven Gerrard, conceded his side had plenty of work to do after a 1-0 home win over Russia’s Ufa.
Poor defending had seen Celtic knocked out of the Champions League qualifiers by AEK Athens last week.
After taking a third minute lead through Olivier Ntcham, they conceded another soft goal 10 minutes later when Ovidijus Verbickas headed home from a free-kick.
The Scottish champions enjoyed the lion’s share of possession without carving out too many opportunities.
While they will be favourites to advance, manager Brendan Rodgers said his side had to tighten up at the back.
“We gave away a soft goal. That is a real, real concern now,” he told the club’s website.
“We are not giving away many chances, but we don’t defend the set-piece well enough.
“We seemed to lack concentration, which was a problem for us, and we lacked pride in terms of defending. I think that’s pretty clear,” he added.
“Games like that, especially away from home, you need to demonstrate that hunger not to concede. It was too easy.”
City rivals Rangers will carry a slender lead to Ufa in the autonomous republic of Bashkortostan next week.
Former England captain Gerrard said they would need a battling performance to reach the group stage of the tournament.
“We won’t be getting carried away. We understand and respect the opposition and we need a performance full of heroes and warriors next week,” he told reporters.
“But we’re capable of going there, being hard to play against and defending well like we’ve shown before. We’re also capable of getting an important away goal.”
Rangers are unbeaten in 10 matches under Gerrard who took over in May and has brought in 12 players.
He looks to end Celtic’s run of seven successive Scottish Premiership titles. (Reuters/NAN)