The Austrian custodian, 25, was exceptional during The Gunners' 1998 Double-winning campaign but could not establish himself as first choice between the sticks and was loaned out to Fiorentina last season.
The cash-strapped Viola could not afford to sign the shot-stopper and Espanyol moved in with the player now hoping to show Wenger that he was in fact good enough to don the number one jersey at Highbury.
"David (Seaman) has opted to stay which means he will be the automatic first choice for Arsene," Manninger told the Evening Standard.
"That will make it obvious that I was right to go but I thought this was my club, my city and that I would become Arsenal's first-choice goalkeeper.
"Coach Bob Wilson and Arsene know I'm a good goalkeeper but they will see me doing my job here in Spain, they will see how well I play and I know they will have to turn to each other and admit they made a mistake."
