Extroverted welterweight Shonie Carter (Pictures) has withdrawn from a co-featured bout against Luke Stewart (Pictures) at Strikeforce "Melendez vs. Thomson" on June 27 at the HP Pavilion in San Jose, Calif.

Strikeforce middleweight Joe Riggs (Pictures) 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.

One of the more seasoned figures of the game, the 36-year-old Carter has clocked in over 60 MMA bouts to his name, which includes six UFC appearances and two recent victories in the WFC and the Palace Fighting Championship.

One-time UFC welterweight contender Riggs made waves last September with a dominating performance over Eugene Jackson (Pictures) at Strikeforce's star-studded event at the Playboy Mansion in Los Angeles.

A feared competitor for his knockout hands and powerful ground-and-pound warfare, "Diesel" was temporarily derailed by Cory Devela (Pictures), when the Washington native threw Riggs onto his back at "Strikeforce at the Dome" last February. Riggs, who had previously undergone back surgery, was forced to tap out on impact. Riggs underwent a second surgery that month to repair spinal cord damage.

Stewart has been touted as one of the more promising up-and-comers in the Strikeforce stable. After cinching five bouts in a row, the San Francisco jiu-jitsu stylist was finally stopped by Tiki Ghosn (Pictures) via decision at Strikeforce's "Shamrock vs. Le" event last March.

In the main event, Strikeforce lightweight champion Gilbert Melendez (Pictures) will defend his title against revered American Kickboxing Academy product Josh Thomson (Pictures).