Sherdog's Loretta Hunt has the scoop:

Extroverted welterweight Shonie Carter has withdrawn from a co-featured bout against Luke Stewart at Strikeforce "Melendez vs. Thomson" on June 27 at the HP Pavilion in San Jose, Calif.

Strikeforce middleweight Joe Riggs has agreed to step into the vacant slot on a week's notice. The bout will be contested at a catch-weight of 178 pounds, confirmed Strikeforce representative Mike Afromowitz.

Carter told Sherdog.com that he shattered a knuckle in his hand while training and was fearful he wouldn't pass the California State Athletic Commission's physical examination next week to proceed with the bout.

It seems awfully quick for Riggs to be returning to action after re-injuring the back he'd just had surgery on. It's been less than four months since that bout with Cory Devala, in which time he's had another procedure ("to repair spinal cord damage"), nevermind the fact that he's taking this fight on a week's notice. Then again, maybe "Diesel" knows what he's doing: Stewart's last fight was a unanimous decision loss at the hands of another crafty veteran, Tiki Ghosn.