Britney / Minaj Tour?

Britney Spears has reached out to Nicki Minaj as her opening act for her upcoming concert tour ... and lawyers for the two are in "serious talks." We're told it's looking very good that Nicki and Britney will reach an agreement in the next day or so.

Nicki would take the place of Enrique Iglesias -- who bailed at the last minute because his ego could not take opening for Britney.

Nicki is currently on tour with Lil Wayne -- those concerts end on April 28. Britney's tour begins June 17 in Sacramento.