Arsenal: Arsene Wenger has been handed a massive boost as Laurent Koscielny returned to training on Tuesday.
The French defender was released from international duty in early October after a recurrence of the of his persistent Achilles injury but will likely START if the problem doesn't flare up prior to kickoff.
Ilkay Gundogan completed 90 minutes at the weekend and could now make his first Champions League start since scoring in the 2013 Final at Wembley.
Sokratis Papastathopoulos may play, despite a fractured leg. The Gunners are all over the place as a side, particularly as the second half comes to the boil.
Again at the weekend, Arsenal's defending was amateurish. The midfield lacks patience, all too willing to get ahead of the play and into the final third without working the ball there astutely, while the full-backs are too eager to do similar, leaving gaps.
Against Klopp's all-action Dortmund, they can't afford to leave space, either between the lines or in behind.
Doing what they did against United will once more prove suicidal.
As such, they need a big showing from Per Mertesacker.
The giant German needs to organise those in front of him, both when the side are in possession and when defending.
Having not ever been blessed with pace, such organising of teammates comes naturally to the World Cup winner.
Arsenal will look to get over their weekend loss against Manchester United by ensuring their qualification to the knockout stages of the Champions League when they face Borussia Dortmund on Wednesday evening.
The Gunners have taken seven points from their four group games so far, but it was in Dortmund on Matchday One when they were beaten, losing 2-0 at the Westfalenstadion.
They should have made qualification safe in their last home game, but threw away a three-goal lead against Anderlecht in embarrassing fashion.