Just found this on mmaweekly:
Strikeforce vice president Mike Afromowitz on Wednesday confirmed that the promotion's light heavyweight champion, Bobby Southworth, will defend his title against Renato "Babalu" Sobral on Sept. 20 when Strikeforce returns to the Playboy Mansion in Beverly Hills, Calif.

"He is the protector and I am the hunter," said the 32-year-old Sobral, a former UFC championship challenger and Brazilian national wrestling champion. "I am already in shape and prepared to take it from him. I want to be the new Strikeforce world champion and, if I could become champion while fighting at a venue like the Playboy Mansion, that would make a good win even better."

The 38-year-old Southworth most recently defended his title at on June 27 as part of the Strikeforce "Melendez vs. Thomson" event in San Jose, Calif. He defeated Anthony Ruiz in a rematch of a non-title bout that Southworth lost late in 2007.

Strikeforce At The Masnion II is scheduled to be a 10-bout fight card. Already announced is a bout between MMAWeekly.com's No. 6 ranked middleweight fighter, Kazuo Misaki, and Joe Riggs. Afromowitz on Wednesday also confirmed the participation of Strikeforce lightweight champion Josh Thomson and undefeated lightweight sensation Billy Evangelista.