After an earlier announcement about the event’s championship headliner, UFC 188 now has an intriguing co-headliner.

Officials today announced former Bellator MMA lightweight champion Eddie Alvarez (25-4 MMA, 0-1 UFC) and former Strikeforce titleholder Gilbert Melendez (22-4 MMA, 1-2 UFC) will square off at the event.

UFC 188 takes place June 13 in Mexico City. A venue has not been announced, but the UFC’s inaugural trip to the country and city took place at Mexico City Arena in November. In UFC 188’s headliner, which was announced earlier today, long-reigning heavyweight champion Cain Velasquez (13-1 MMA, 11-1 UFC) meets interim titleholder Fabricio Werdum (19-5-1 MMA, 7-2 UFC).

The main card, including the co-headliners, airs on pay-per-view following prelims on FOX Sports 1 and UFC Fight Pass.

Melendez is No. 6 and Alvarez is No. 8 in the latest USA TODAY Sports/MMAjunkie MMA lightweight rankings.

Alvarez recently made his long-awaited UFC debut after an extended contract fight with his former home at Bellator. However, at UFC 178 in September, the 31-year-old got a tough test and suffered a decision loss to surging Donald Cerrone in his promotional debut. Prior to the setback, the hard-hitting Alvarez was on a 10-1 run that included a string of dominant wins under the Bellator banner.

He now meets Melendez, whom he’s previously sparred with in the media while discussing a potential bout. Melendez recently returned from a 14-month layoff, due to in part to a contract renegotiation, and suffered a title loss to champ Anthony Pettis after their coaching stint on “The Ultimate Fighter 20.” The 32-year-old, who won seven straight fights from 2009-2012, is now 1-2 in his past three bouts, which also included a UFC-debut loss to then-champ Benson Henderson in 2013.

For complete coverage of UFC 188, stay tuned to the UFC Rumors section of the site.