Here we go again.

Rory MacDonald has suffered an undisclosed injury in training, forcing him out of his scheduled rematch against former Ultimate Fighting Championship (UFC) interim Welterweight champion Carlos Condit.

MMA Fighting delivered the unfortunate news earlier today.

"Ares" and "The Natural Born Killer" were set to tangle in the co-main event at UFC 158, which takes places at Bell Centre in Montreal, Quebec, Canada, on March 16, 2013. It is a pay-per-view (PPV) main card the features the much-anticipated showdown between current 170-pound kingpin Georges St. Pierre against Nick Diaz in the main event.

MacDonald and Condit initially met back at UFC 115 two years ago with the latter getting the best of the Canadian sensation in the final seconds of the third and final round, compelling a controversial stoppage from the referee.

"Ares" was last seen defeating B.J. Penn at UFC on Fox 5 last December, while Condit came up short against "Rush" at UFC 154 the month before. No word on who Condit will face in MacDonald's absence and/or if he will remain on the UFC 158 card altogether.

Stay tuned to MMAmania.com as more details become available. In the meantime, be sure to check out the latest UFC 158 fight card and rumors right here.