Lyon's 2-1 loss at home to lowly Caen served as a stern reminder that the club's policy of blooding young players needed some polishing three days before they meet the first Cypriot team to make the knockout stages.
With a new coach this season and virtually no money to recruit, Lyon have reached the League Cup final, are still in a position to win the French Cup and look capable of qualifying for next season's Champions League through Ligue 1.
However, Saturday's performance shocked many at the club.
"It is a disappointment. We're coming down to earth with a bump," president Jean-Michel Aulas told the Lyon website.
"We have to look into what went wrong and use this for the Champions League on Tuesday. We have to question ourselves on all levels."
Coach Remi Garde, who took over from Claude Puel on a one-year contract, has been blending in young players but they have been found wanting at times this term.
Maxime Gonalons, 22, lacked steel in the midfield while Clement Grenier, 21, failed to add stamina when needed against Caen. Only substitute striker Alexandre Lacazette, 20, managed to offer a threat, winning a late penalty.
French striker Bafetimbi Gomis promised they would do better on Tuesday, saying: "It will be another story."
Lyon, who reached the Champions League semi-finals in 2010, are also likely to face defensive troubles against APOEL.
Croatia centre-back Dejan Lovren looks set to miss the game through injury, possibly forcing Garde to field 18-year-old Samuel Umtiti although Cris could return on Tuesday.
Playmaker Yoann Gourcuff is still out of form.
While Lyon needed a 7-1 thrashing of Dinamo Zagreb to seal unlikely qualification for the last 16 for a ninth straight season, APOEL topped their group having beaten heavyweights Porto and Zenit St Petersburg.
APOEL's defensive strength could prompt another backs-to-the-wall performance at the Stade Gerland after Ivan Jovanovic's side managed three away draws in the group stage.
They will be attempting to beat Lyon at home at this stage for the first time since AS Roma recorded a 2-0 win in 2007 but will be aided by new Portuguese utility man Helder Sousa.
APOEL's band of Cypriots, Greeks, Brazilians, Portuguese, Macedonians, Bosnians, Argentines, Tunisians and Spanish have shown that a strong team bond can trump individual brilliance.
"I am the happiest man in the world right now," Jovanovic said in November. "We want to celebrate more great nights along with, not just our own fans, but all Cypriot fans back home."
Champions APOEL, in the running for the Cypriot title again, played their last league game on Friday and beat Ethnikos Achnas 2-1 with Constantinos Charalambides scoring both goals.
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