A middleweight superfight between champion Gegard Mousasi and welterweight titleholder Rory MacDonald is in the works for a Bellator event Sept. 29 in San Jose, Calif.

ESPN.com today reported the bout has been booked, though two people with knowledge of the situation, including a Bellator official, said a deal has not yet been finalized. The people asked for anonymity because they weren’t authorized to speak on the record.

The potential fight would be the first champion-vs.-champion showdown in Bellator’s history. Former bantamweight and featherweight champ Joe Warren attempted to capture the titles concurrently but failed to do so.

The matchup also marks a shift in strategy from Bellator President Scott Coker, who on two separate occasions said he would not pursue an immediate showdown between Mousasi and MacDonald. Earlier this month, Coker indicated the two were on separate schedules, and MacDonald would be first to fight.

The fighters, however, have been on the same page in wanting their next bout to be against each other.

After capturing the middleweight title from Rafael Carvalho last month at Bellator 200, Mousasi called out MacDonald in no uncertain terms. MacDonald, meanwhile, badgered Coker to put the fight together.

MacDonald most recently fought in January at Bellator 192, when he captured the welterweight title from Douglas Lima.

If confirmed, the superfight is likely to join a fight between Quinton Jackson and Wanderlei Silva, who recently announced on social media a fourth showdown with his rival.

For more info on the Bellator event on Sept. 29, check out the MMA Rumors section of the site.