Arsenal midfielder Mesut Ozil was ill before the club's Champions League fixture against Borussia Dortmund this week, Arsene Wenger revealed in his Friday pre-match press conference.

While Ozil was not at his best during the encounter at the Emirates Stadium, the German was still Arsenal's best creative outlet on the night—supplying four chances for his side, per Who Scored.

Wenger, though, has now offered reasoning for Ozil's subdued showing.

ESPN.co.uk provides the full quotes:

He was sick before the game and he was not at his best on the night. He said he felt alright, but in the two days before he had a virus and you could see that physically he was not at his best. Dortmund were organised to stop us from playing our game and one of their game plans was to stop Ozil to get in the game. They did that well. On top of that, Ozil was not at his best physically on Tuesday night.

Since arriving in North London, the Germany international has quickly become essential to Wenger's side during their rise to the top of the Premier League table.

With two goals and three assists in his five league appearances to date, he is making meaningful contributions. With better finishing from teammates, he could perhaps have more assists to his name already.

Having cost in excess of £40 million, such an impact is somewhat of a necessity. However, when Ozil is not at his best, the Gunners still need others to step up and take up the reins.

There is no suggestion, though, that Ozil will be a doubt for the Crystal Palace game on Saturday, when Arsenal will take on the manager-less Eagles side.

It should be a relatively comfortable game for Wenger and his men, perhaps offering a chance to rest the German ahead of a busy schedule over the next couple of months. If Ozil is slightly below par, it may be worth leaving him on the sidelines.

Next weekend's game against Liverpool, as well as the subsequent return fixture against Dortmund, will be the next tests for Arsenal and it is for those encounters that they need Ozil firing.

With Palace on Saturday and then a Capital One Cup tie against Chelsea in midweek, there is ample opportunity for Wenger to ensure that Ozil arrives at the Liverpool fixture in peak condition.

The first encounter with Dortmund is now gone. With three sides in Group F level on six points, Arsenal need to attempt to pick up a point in the away fixture.

On the night, it will be to Ozil that Arsenal will look for inspiration once more.