Set for August 23 from the BOK Center, the bout is added to a lineup just now starting to take shape. The other fights confirmed feature Wilson Reis and Tim Elliott at flyweight and Tom Niinimaki and Chas Skelly at featherweight.
The 30-year-old Alves (20-9) returned after a two-year layoff to defeat Seth Baczynski this past April. He is 3-4 in his last seven, including decisions losses to Jon Fitch and Georges St-Pierre for the UFC welterweight title.
Mein (28-9) rebounded from a 2013 loss to Matt Brown in April, defeating Hernani Perpetuo via split decision. He is 2-1 inside the Octagon, and 10-2 in his last 12, including wins over Dan Miller, Josh Burkman and Joe Riggs.