Roy Nelson to fight Dave Herman

Heavyweight Roy Nelson has yet another opponent for his May 26 bout at UFC 146.

Nelson's previously scheduled opponent, Gabriel Gonzaga, withdrew from the fight with an undisclosed injury, and has been replaced by Dave Herman, UFC announced Tuesday night.

Herman represents the third opponent slated to face Nelson at UFC 146, which will be held in Las Vegas.

Nelson was originally booked to take on Antonio "Big Foot" Silva, but the Brazilian jiu-jitsu black belt was removed and pitted against former champion Cain Velasquez.

Silva replaced Velasquez's original opponent, Frank Mir, who is now scheduled to fight current heavyweight titleholder Junior dos Santos in the UFC 146 main event.

The heavyweight musical chairs began when former Strikeforce champion and UFC top contender Alistair Overeem was taken off the card after failing a random prefight drug test.

Herman, a hard striker who has registered 15 knockouts in 24 professional fights, will carry a 21-3 mark into his bout with Nelson. He will look to rebound from a second-round TKO at the hands of Stefan Struve on Feb. 15.

Gonzaga isn't the only fighter forced to withdraw from UFC 146.

Lightweight contender Evan Dunham also suffered an undisclosed injury that has forced him out of a highly anticipated showdown with fast-rising Edson Barboza.

With Dunham unable to participate, Barboza now faces veteran Jamie Varner.

A former WEC lightweight champion, Varner fights under the Zuffa LLC banner for the first time since he was released from the promotion in December 2010.

Varner returns to the Octagon with a pro mark of 19-6-1 and two no-contests. He is currently riding a two-fight win streak.