The rematch will have to wait, but UFC light heavyweight champion Jon Jones (20-1 MMA, 14-1 UFC) still has a big fight on the horizon.

UFC officials today announced a training injury has forced Alexander Gustafsson (16-2 MMA, 8-2 UFC) out of a planned UFC 178 main event with Jones, and Daniel Cormier (15-0 MMA, 4-0 UFC) will instead challenge for the belt at the Sept. 27 event, which takes place at Las Vegas’ MGM Grand Garden Arena.

Jones is currently ranked No. 1 in the USA TODAY Sports/MMAjunkie MMA light heavyweight rankings. Cormier, who’s ranked No. 3, replaces No. 2 Gustafsson.

Cormier, a former Strikeforce heavyweight grand prix champion, has long made clear his intentions of facing Jones for the belt. A two-time Olympic wrestler, Cormier made the move to 205 pounds earlier this year with the sole intention of a title showdown. He’s already picked up light-heavyweight victories over Dan Henderson and Patrick Cummins and was hoping to jump ahead of Gustafsson in the line waiting to fight for the title.

He’s now done that, albeit in a less direct fashion that he originally intended.

Meanwhile, Jones has previously asked for the matchup, as well, hoping to silence a vocal Cormier before turning his attention to the rematch with Gustafsson. Instead, UFC officials elected to book Gustafsson first, giving the man who gave Jones his stiffest career test to date a second chance and dethroning the dominant champ.

Now Gustafsson will have to get back in line. A timetable for his return wasn’t immediately established.

With the change to the lineup, UFC 178 now includes:

Champ Jon Jones vs. Daniel Cormier – for light heavyweight title

Conor McGregor vs. Dustin Poirier

Dominick Cruz vs. Takeya Mizugaki

Tim Kennedy vs. Yoel Romero

Amanda Nunes vs. Cat Zingano

Brian Ebersole vs. John Howard

Patrick Cote vs. Stephen Thompson

For more on UFC 178, check out the UFC Rumors section of the site.

(Pictured: Daniel Cormier)