Sources close to Enrique tell Hollyscoop he pulled out because he doesn't want to be an opening act--for anyone.
Another reason could be the outrageous prices Britney is charging. Tickets start at $96-346. That's a lot of dollars per lip-synched song.
Enrique has been tweeting about his tour all week long with no mention of Britney.
Story developing...stay tuned for more details!