Joe “Diesel” Riggs (30-10) and Nick Diaz (20-7) will add a new chapter to their infamous, hostile rivalry when they square off in the first-ever STRIKEFORCE world welterweight (170 pounds) championship bout at San Jose, California’s HP Pavilion on Saturday, August 15. The rematch between the two stars represents the fourth title fight that will unfold at the STRIKEFORCE: “Carano vs. Cyborg” mixed martial arts (MMA) mega-event.

Riggs and Diaz faced off for the first time at UFC 57 in Las Vegas, Nevada on February 4, 2006. Following the completion of the third and final round of action, Riggs was awarded a unanimous judges’ decision.

The fight that should have ended in the cage, however, re-started after the two crossed paths in the local hospital that they visited for medical treatment following their grueling bout. Law enforcement was needed to put an end to the scuffle.

“I’m going to knock him the hell out. It’s the only legitimate way to shut this guy up,” said a pumped up Riggs who, in his last start, ran to a one-sided unanimous decision victory over power punching brawler “The NY Badass” Phil Baroni at STRIKEFORCE’s inaugural event at Scottrade Center in St. Louis, Missouri on June 6.

“Nick’s a great fighter and everything. He hasn’t lost in a while either. I think I’ve got his number, though.”

The 25-year-old Diaz, who has been on fire of late, will enter the rematch unbeaten in his last five fights. None of his last five opponents were able to take him the distance of their respective bouts.

“I won the fight last time and I’m going to win this time. It’s that simple,” said Diaz a Brazilian Jiu-Jitsu black belt who fancies western boxing and frustrating opponents with his long reach.

In his last effort, the 25-year-old Cesar Gracie protégé submitted the ever-resilient Scott “Hands of Steel” Smith with a rear-naked choke in the third round (1:41) of their matchup at STRIKEFORCE’s event in St. Louis on June 6.

On April 11, Diaz shocked the world by dominating and stopping four-time world champion and MMA legend Frank Shamrock in the second round of their STRIKEFORCE main event showdown at HP Pavilion.

“I didn’t think the rematch was actually going to happen,” continued Diaz, “because it didn’t seem like he wanted to fight me again. So, I’m surprised and looking forward to this fight.”

In the main event on August 15, mixed martial arts’ (MMA) leading lady, the undefeated and extremely popular Gina “Conviction” Carano (7-0), will square off with rival powerhouse Cris “Cyborg” (7-1) in what is one of the most eagerly anticipated battles of all time.

Carano and Cyborg, the consensus two best female fighters in the world, will be the first women in MMA history to headline a major MMA fight card. In addition, they will fight for the first STRIKEFORCE 145-pound Female Championship.

STRIKEFORCE World Heavyweight Champion Alistair “The Demolition Man” Overeem (29-11) will put his coveted title on the line and, at the same time, attempt to avenge a previous defeat when he squares off with old nemesis and two-time Brazilian Jiu-Jitsu World Champion Fabricio “Vai Cavalo” Werdum (11-4-1)

STRIKEFORCE World Lightweight (155 pounds) Champion Josh “The Punk” Thomson (16-2) will set out to defend his crown against Gilbert “El Nino” Melendez (15-2), the man whom Thomson dethroned by way of unanimous decision at HP Pavilion on June 27, 2008.

Tickets for STRIKEFORCE: “Carano vs. Cyborg,” priced from $30, are on sale at the HP Pavilion box office (408-287-7070) as well as at all Ticketmaster locations (800-745-3000), Ticketmaster online (www.ticketmaster.com), and the official STRIKEFORCE website (www.strikeforce.com).

HP Pavilion doors will open for the event at 5 p.m. The first preliminary bout will begin at 5:30 p.m.

The live SHOWTIME telecast of STRIKEFORCE: “Carano vs. Cyborg” will begin at 10:30 p.m. ET/PT (tape delayed on the west coast).

After co-promoting two events live on SHOWTIME in 2007 and 2008, STRIKEFORCE in March 2009 signed a multi-year agreement to stage live MMA events on the premium cable television network.