"I don't give the team out today, I will give it out on Thursday", the Frenchman added.
"First of all, he has to continue to work with the spirit that he works and focuses", explained the French boss.
"We need to keep the focus high and always improve ourselves", he told reporters.
Forward Alexis Sanchez could play in order to regain match fitness, following his delayed start to the season, while injury-plagued Jack Wilshere is in contention for a first Arsenal appearance since May 2016.
Cologne supporters cheer during the Europa League Group H soccer match against Arsenal. Kirsty Wigglesworth
The twice Bundesliga champions and 1986 UEFA Cup runners-up finished a creditable fifth last term in Germany but arrive in London on the back of three league defeats, 1-0 away to Gladbach, a 3-1 home defeat by Hamburg and a 3-0 loss to Augsburg.
"His game, you have certainly seen the video of him when we played against Barcelona, his game is about that", Wenger said, highlighting a particularly impressive display against the Catalan giants in 2011.
According to The Independent, the players were excused from training on Wednesday morning as they will not be involved on Thursday. "We got 75 points past year and overall, I am humble enough to be happy to win every competition".
"You have to not get caught in your mind with preconceived ideas, football is down to how you perform on the day".
However, Alexis Sanchez is likely to start the match, after training in the last three days following his appearance off the bench against Bournemouth.
However, the Europa League presents what is most likely Arsenal's best chance in Europe since reaching the final of the Champions League in 2006.