Ozil has impressed since his deadline-day move to the Emirates Stadium and the left-back is surprised that the Gunners were allowed to sign him.
Asked by Marca if the switch surprised him, Monreal replied: "Personally, I think so. Mesut is a star and Real Madrid are full of stars. I didn't expect Madrid to let him go.
|8/1||Spain are 8/1 with Bet365 to beat Equatorial Guinea 4-0|
Ozil is expected to head to World Cup 2014 with the Germany squad but Monreal is a little more concerned over his own place.
Though the defender has been called up for Spain’s friendlies against Equatorial Guinea and South Africa, he is behind Kieran Gibbs in the Arsenal pecking order and Jordi Alba at international level.
"I would like [to go to the World Cup]," he added. "I'm conscious that it's not going to be easy, also in part because I'm not playing the minutes that I would like with Arsenal, [but] I'm going to keep fighting because I really want to be at the World Cup."
Monreal feels, however, that playing in the Premier League gives his chances a boost.
"I think so. I was at Malaga for a year and a half and I grew a lot as a player [but] the move to the Premier League is a jump in quality and a step up," he remarked. "I think that being part of a team like Arsenal helps."