During his post-UFC 130 'Observer Radio' program last night, Dave Meltzer said (during a conversation with Mike Coughlin and Bryan Alvarez) that Showtime has reportedly nixed a fight between Nick Diaz and UFC Welterweight Champ Georges St. Pierre. 

Meltzer said he believed Showtime's reasoning to have something to do with not wanting their star to be embarrassed by a fighter from a different promotion. Meltzer also cited a fear by Showtime regarding not wanting to take a ratings hit in the future if Diaz were to lose the fight.

At this point, there has been no official word from Showtime or Strikeforce to confirm if this report is true. It is worth noting that Meltzer also recently reported that the UFC would likely make GSP and Diaz the coaches for the next season of The Ultimate Fighter. 

If the report is true, it would be puzzling in light of Diaz's recent announcement that he would no longer be pursuing his boxing match with Jeff Lacy. All the pieces did appear to be in place for the GSP-Diaz fight to take place.

However, it would explain why there has been such a blatant absence of news about who the next opponents will be for St. Pierre and for Diaz, and why Dana White recently came out and announced that the fight would definitely not occur in Montreal at UFC 140.

We will keep you posted regarding any new developments. 

(Props to Cageside's Keith Harris for getting the initial scoop)