Two of MMA's most brash and controversials personalities will collide when Nick Diaz and Frank Shamrock face off in the main event of Strikeforce's upcoming event on April 11th at the HP Pavillion in San Jose, scheduled to be broadcast on Showtime as part of Strikeforce's new deal with the network and Pro Elite.  There were rumors of this fight floating around in the days since the Strikeforce announcement, but Sam Caplan at Five Ounces of Pain confirmed early this morning that the fight is on.  An official announcement from Strikeforce is likely on Tuesday.

The matchup had been rumored for the past several days but FiveOuncesOfPain.com was able to confirm early Wednesday morning that the fight has been finalized. An official announcement could be made Tuesday during a joint conference call to be hosted by Strikeforce and television partner Showtime.

Shamrock, 23-9-2, fights at 185 pounds while Diaz, 18-7, primarily has competed at 160 and 170 pounds. As such, it was not immediately clear what weight the fight between the two California-based fighters will be contested at. However, Diaz has gone on the record before in interviews and stated that he would have no issue going up in weight if the right opportunity presented itself.

As the report mentions, no official weight for the bout has been decided upon yet, although it's likely a catchweight will be established.  More information on that matter will probably become available when Strikeforce makes their official announcement.

Shamrock, a true legend of the sport, is a former King of Pancrase, UFC middleweight champion, and Strikeforce middleweight champion.  Usually considered the first true "mixed martial artist", Shamrock was a prototype for current stars like Georges St. Pierre who combine precise and deadly striking with excellent wrestling and dangerous submissions.  He last competed nearly a year ago in March of '08, suffering a third round TKO loss to Cung Le in a Strikeforce middleweight title bout, breaking his arm after a kick from Le.  The bout was a standup war, although many were surprised by Shamrock's stubborn refusal to take the fight to the ground where it was assumed he would have a considerable advantage.

In Diaz, Shamrock will face a fighter 11 years younger than him, but one who still carries 25 fights worth of pro MMA experience into the cage.  Diaz is known as much for his trash-talking and out-of-the-ring antics, as he for his outstanding grappling and precise boxing.  The Cesar Gracie-trained black-belt in Brazilian jiu jitsu has competed in nearly every major organization, incuding the UFC, Pride, Shooto, EliteXC, Dream, and WEC.   Diaz last saw action in July '08 where he stopped Thomas Denny with strikes in the second round at EliteXC's penultimate event.

An interesting sidebar to this fight is the minor feud between Shamrock, and Diaz's coach and teacher, Cesar Gracie, which led to a bout between the two under the Strikeforce banner in March '06, with Shamrock KO'ing Gracie just 21 seconds into the fight.  The Shamrock vs. Gracie card set the all-time record for attendance at a North American MMA event, drawing over 18,000 fans to the HP Pavillion.

It will remain to be seen if Shamrock and Diaz will come close to that number at HP in April, but I for one am eagerly awaiting the trash talk to start flowing out of two of the best mouths in the business.