Jurgen Klopp says something in the Arsenal squad has clicked since the signing on Mesut Ozil.
The German international has impressed for the Gunners since joining from Real Madrid in the summer, helping Arsenal to the top of both their Champions League group and the Premier League.
They face Borussia Dortmund at the Emirates stadium on Tuesday knowing a win will see them all-but qualify from arguably the toughest group of this season's competition.
Arsene Wenger's men have won 11 of their last 12 games and look in good shape to end their eight year trophy drought.
Dortmund manager Klopp believes Ozil is the piece Arsenal have been missing during this baron spell.
He told reporters: "This team missed one player and maybe it can be Mesut Ozil. He is technically perfect, he is fast and has developed a drive to goal.
"He is very intelligent, can play in any team. He has everything, is natural and it works very well. That is why it was a great idea from Arsenal and not so from the one who let him go."
Klopp went on to praise Arsenal's British midfielders Aaron Ramsey and Jack Wilshere for providing the goods during the injury of Santi Cazorla.
Cazorla was key to Arsenal's play last season but Klopp believes the emergence of Ramsey has taken the weight off of the Spaniard's shoulders.
He continued: "One year ago no-one thought it was possible they could play brilliant football without [Santi] Cazorla, now they have some injuries and still look strong with Ramsey and Wilshere, Rosicky is back in shape and Giroud, he is one of the best."