Borussia Dortmund head coach Thomas Tuchel baulked at the notion of Cristiano Ronaldo not being on top form ahead of his side facing Real Madrid at Signal Iduna Park.
Both sides won their opening matches in Group F, with Ronaldo on the scoresheet to launch a late comeback in Madrid's 2-1 triumph over Sporting CP.
But the three-time Ballon d'Or winner has not found the net in two subsequent appearances and was substituted during Saturday's 2-2 LaLiga draw at Las Palmas.
Nevertheless, Tuchel expects Ronaldo and his team-mates to be firing on all cylinders during one of the stand-out ties of the group stages.
"Cristiano is not in form? Who am I to say," the Dortmund boss told a news conference.
"He is one of the best footballers in the world, a winner. We expect him at his best.
"We're preparing for Real Madrid in their best form. Of course we acknowledge Real's quality. It will be huge task to defend against them.
"We will need a lot of awareness, we need to be disciplined to switch from attack to defence. We need good possession stints."
Star striker Pierre-Emerick Aubameyang is fit to feature despite sustaining a bruised foot during Friday's 3-1 win over Freiburg, where he opened the scoring.
Former Barcelona defender Marc Bartra (adductor), forwards Andre Schurrle (knee) and Adrian Ramos (adductor) are all back in contention to face the defending European champions, as Tuchel's free-scoring side look to build on their 6-0 thrashing of Legia Warsaw in the opening group game.
"Of course we want to utilise Aubameyang's and [Ousmane] Dembele's pace. In the end you have to be ready for every facet of the game." Tuchel explained.
"It won't be just about being in possession, it won't just be about transition. We have have to treat each situation individually. We need to be brave enough to capitalise on the moment, when it presents itself.
"Our team currently has a very positive aura. They show great impetus and they able to focus on point. We will get to know our team against perhaps the biggest name in football, all in a great atmosphere."
Madrid overcame Dortmund in the quarter-finals on their way to lifting the Champions League in 2014, although they were beaten at the semi-final stage by their German opponents the season before.
The sides also met in the group stage during 2012-13, sharing a 2-2 draw at Santiago Bernabeu after Dortmund won 2-1 at home.