Arsenal travel to Germany to face Borussia Dortmund for yet another time in the Champions League group stage, but injuries have put the Gunners on the back foot ahead of this evening's clash.
Arsene Wenger only has three fully fit first-team defenders to play, with first-choice Per Mertesacker and Laurent Koscielny as centre-halves and Kieran Gibbs as a left-back.
However, Arsenal's £16million new recruit Calum Chambers is doubtful for tonight suffering with tonsillitis, and this leaves Wenger also in doubts of what's going to happen in Germany at the Westfalenstadion after the Frenchman described the 19-year-old defender as a top quality.
"That's a very important quality when you're a young boy playing at a big club. His transition game is fantastic. He's very quick and his final ball is good as well. He lacks a bit of experience as a defender, but he's very dangerous going forward", Wenger told BBC Sport.
Nacho Monreal did not travel with the squad due to a back problem, while Mathieu Debuchy who was already suspended may be out for much longer due to an ankle ligament damage.
Reports claim that the French defender could be ruled out for up to three months.
Wenger said "The Debuchy injury puts us a little bit in a position where we do not want more and hopefully we have good news after his scan today and he will be back soon.
Concerning Klopp's side, the Germans will miss the likes of Marco Reus who sprained an ankle; Ji Dong-won and Olivier Kirch, both are yet to start with the club this season after picking a muscle injury.
Dortmund have been in a good form last season, finishing second of the Bundesliga, but also recently with four wins in a total five matches in all competitions since August.
And with Japanese midfielder Shinji Kagawa who returned to his former club after two frustrating season at Old Trafford, the player has already been sensational for the German side, scoring his first since his reunion with the club in last weekend game against Freiburg.
Klopp told Sky Sports: "I was kind of surprised Kagawa was on the market again.
"His first year at Manchester United was Sir Alex Ferguson's last year, so that isn't the time to develop players.
"The only thing you want at that stage is results and titles.
"Kagawa's second year at United was the first year of the new coach, so that's also all about results.
"Then there was a third manager. So we saw the chance to sign Kagawa and we took it. Kagawa was sensational against Freiburg."
Doubts on Arsenal
Meanwhile, Arsenal have only won one of their first-four Premier League matches so far and it leaves the doubt of whether the Gunners can repeat a good run in the Champions League this year.
But the likes of Danny Welbeck, who joined the Emirates on transfer deadline day for a deal worth £16million, should bring more pace and chances to score, as he might be the solution of Wenger's consistent problem upfront.