A high-profile lightweight contest between two top contenders has been scrapped, as Michael Chiesa (14-2 MMA, 7-2 UFC) has been forced to withdraw from UFC Fight Night 91.

MMAjunkie today confirmed with UFC officials that the promotion is now seeking a replacement opponent for Tony Ferguson (20-3 MMA, 10-1 UFC) willing to step in on a little more than two weeks’ notice.

Back troubles forced Chiesa out of the fight, and Cheisa took to Facebook to say he’s hoping eight weeks of rehab will be enough for him to heal.

To my family, friends and fans. As reported below, a back injury has forced me out of my scheduled fight for July 13th against Tony Ferguson. During a routine training session, I felt a pop and shift in my lower back followed by very very sharp pains that left me on the floor.

I found out today I have a fully ruptured disk, I will undergo 8 weeks of physical therapy and rehab to hopefully avoid having to go under the knife and get back surgery. Thanks to everyone that supports me, my teammates and coaches, the city of Spokane and all my fans around the world. I’ll be back stronger. – Mav

Ferguson is currently ranked No. 3 in the latest USA TODAY Sports/MMAjunkie MMA lightweight rankings, while Chiesa checks in at No. 10.

UFC Fight Night 91 takes place July 13 at Denny Sanford Premier Center in Sioux Falls, S.D. The main card airs live on FOX Sports 1 following prelims on FOX Sport 1 and UFC Fight Pass.

It’s familiar territory for Ferguson, who was expected to face Khabib Nurmagomedov at this past December’s The Ultimate Fighter 22 Finale card, only to see his opponent injured and replaced by Edson Barboza. Ferguson and Nurmagomedov were then slated to meet again at April’s UFC on FOX 19 event, but “El Cucuy” was the one who had to withdraw.

“Maverick,” who won season 15 of “The Ultimate Fighter” reality series, has become one of the most dangerous submission threats at 155 pounds. His six UFC wins by rear-naked choke are the second most in company history, just one shy of Kenny Florian’s all-time record of seven.

With the change to the card, UFC Fight Night 91 now includes:

Tony Ferguson vs. opponent TBA

John Lineker vs. Michael McDonald

Tim Boetsch vs. Josh Samman

Alexey Oleinik vs. Daniel Omielanczuk

Keita Nakamura vs. Kyle Noke

Ben Nguyen vs. Louis Smolka

Ryan Hall vs. Alex White

Cortney Casey vs. Cristina Stanciu

Sam Alvey vs. Eric Spicely

Matthew Lopez vs. Rani Yahya

Devin Clark vs. Alex Nicholson

Scott Holtzman vs. Cody Pfister

For more on UFC Fight Night 91, check out the UFC Rumors section of the site.