A highly anticipated middleweight matchup has been knocked from next month’s UFC 184 card due to pneumonia.

The illness has taken Ronaldo Souza (21-3 MMA, 4-0 UFC) out of his fight against Yoel Romero (9-1 MMA, 5-0 UFC). UFC officials made the announcement Thursday night, saying the fight is expected to be rescheduled for a later date.

Featuring a pair of championship matchups with UFC middleweight champ Chris Weidman facing Vitor Belfort and UFC women’s bantamweight title holder Ronda Rousey facing Cat Zingano, UFC 184 takes place Feb. 28 at Los Angeles’ Staples Center. The evening’s main card airs on pay-per-view.

“Jacare” Souza has won seven straight fights since losing his Strikeforce middleweight title to Luke Rockhold a little more than three years ago, and six of those seven wins are by stoppage. Since coming to the UFC in the merger with Strikeforce, he has a “Submission of the Night” win over Chris Camozzi, a TKO of Yushin Okami, a decision win over Francis Carmont, and in September, a “Fight of the Night” submission of Gegard Mousasi.

Souza sits at No. 4 in the latest USA TODAY Sports/MMAjunkie middleweight rankings, while Romero is at No. 8.

Romero will put his unbeaten UFC record on the line when the two eventually meet. He went a perfect 3-0 in 2014 with a pair of “Fight of the Night” wins. In January, he stopped Derek Brunson in the third round of a big comeback to win his first bonus of the year. And after a decision win over Brad Tavares in April, he stopped Tim Kennedy in the third round at UFC 178.

The win over Kennedy was a controversial one. Romero was saved by the bell in the second round and wobbled back to his corner. When the third round started, he didn’t get up from his stool, and there was confusion over who was to blame over his stool not being removed in a timely manner, conceivably giving him extra time to recover after the punishment he took late in the second. But just 38 seconds in the third, he stopped Kennedy with a TKO.

The UFC 184 now includes:

Champ Chris Weidman vs. Vitor Belfort – for middleweight title Champ Ronda Rousey vs. Cat Zingano – for women’s bantamweight title Jake Ellenberger vs. Josh Koscheck Holly Holm vs. Raquel Pennington Tony Ferguson vs. Yancy Medeiros Roan Carneiro vs. Mark Munoz Alan Jouban vs. Richard Walsh Roman Salazar vs. Norifumi Yamamoto Derrick Lewis vs. Ruan Potts James Krause vs. Valmir Lazaro Masio Fullen vs. Alexander Torres

For more on UFC 184, check out the UFC Rumors section of the site.