Joe Riggs will not be fighting inside the Octagon for the first time since 2006 later this year after his hand gun accidentally went off while he was cleaning the weapon Monday night.

Riggs, who won the only season of Bellator’s “Fight Master” series, signed back on with the UFC recently. He was expected to meet Paulo Thiago at UFC Fight Night 51 from Brazil, but Sean Spencer will step in for him now.

“We were made aware that newly-signed UFC competitor Joe Riggs was involved in an unfortunate accident (Monday) night,” said the UFC, in a released statement. “While cleaning his permitted firearm (a pistol), the gun discharged, injuring his hand and upper thigh. Riggs was transported to a nearby hospital in Arizona where he is being treated by physicians.

“We wish Joe a speedy recovery.”

Riggs (40-14) went 4-4 in his first stint with the promotion, including a win over Nick Diaz. Thiago (15-7) has lost four straight, while Spencer (11-3) is 2-2 in four Octagon appearances.

Below is the current lineup for the card:

Heavyweight: Antonio Silva vs. Andrei Arlovski

Lightweight: Leonardo Santos vs. Lukas Sajweski

Welterweight: Sergio Moraes vs. Santiago Ponzinibbio

Welterweight: Paulo Thiago vs. Sean Spencer

Welterweight: George Sullivan vs. Igor Araujo

Female Bantamweight: Jessica Andrade vs. Valerie Letourneau

Bantamweight: Rani Yahya vs. Johnny Bedford