I say we play 10 extremely extremely small men and hide them in various positions around the pitch. 4 Corner flags, 4 posts and 2 of Reina's legs, where the most agile of the little men will have to run back and forth at different angles attempting to hide themselves.
City will then assume the match has been postponed and simply wait past the 90 minutes or forfeit players inadvertently by leaving the pitch.
If they play Barry, his hawk like vision may prove a threat, in which case the only reliable course of action is to sacrifice the said little men by forcing fouls. Namely, positioning themselves between the Manchester City players shoes and trying to fit between the studs and/or blades. Some casualties may be incurred but I believe Wembley justifies the loss.