Khedira played alongside Ozil at Real Madrid and is an international colleague of the highly-rated playmaker in the German national side.
He considers the 24-year-old to be among the best players on the planet, and one capable of influencing the destination of major silverware.
Khedira said of Ozil: "Arsenal had a strong team anyway, but Mesut makes them the best team in England.
"I am sure he can be the player that makes things happen for them and win them the championship. Mesut is a genius on the field, there is no other way to describe him."
Khedira was among those to air their frustration at seeing Ozil's sale sanctioned on transfer deadline day, with morale at Santiago Bernabeu having dipped on the back of his departure.
He added: "Of course there was some disappointment among the players at Madrid because he is the best in his position in the world.
"But I understand his decision as a player and also as my friend. He is already playing amazing football for Arsenal and he hasn't even got used to the Premier League yet."