Controversial Strikeforce welterweight Nick Diaz watched his August 15 title fight against Jay Hieron go up in smoke after missing his scheduled pre-fight drug test on August 7 and again today (August 10).

The California State Athletic Commission (CSAC) made arrangements with Strikeforce to reschedule Diaz for today after last Friday's no-show; however, Diaz failed to arrive at the testing facility.

He had until 3 p.m. PT to appear.

The CSAC was unable to accept a sample any later than this afternoon if it was to be processed and reported in time for Saturday's "Carano vs. Cyborg" event. Therefore, Diaz has been removed from his scheduled bout against Hieron and former Ultimate Fighter (TUF) 7 contestant Jesse Taylor will step up to replace him.

From Strikeforce CEO Scott Coker:

Caesar Gracie told me Diaz [missed his Aug. 7 drug test because] he was in the mountains training. He's supposed to be on his way (right now) to Los Angeles to take his drug test with the California State Athletic Commission. He has until 3pm to get it done. We're hoping he makes the right decision. [If he does] we should have the results by Thursday. We have a contingency plan in place if necessary. Regardless, Jay Hieron will be fighting on August 15.

Apparently that contingency plan was "JT Money."

Despite testing negative earlier this year after whooping Frank Shamrock on April 11, Diaz does not exactly have a squeaky-clean history.

Diaz tested positive for marijuana after his surprising and sensational win over PRIDE FC 160-pound champion Takanori Gomi at Pride 33 back on Feb. 24, 2007.

That win was quickly overturned by the Nevada State Athletic Commission (NSAC) and Diaz was suspended for six months. Because of that suspension, Diaz was unable to secure a corner’s license for his brother Nate’s fight against Manny Gamburyan at The Ultimate Fighter Finale 5.

Prior to the Shamrock fight, Diaz told the LA Times he was able to beat drug tests with the help of herbal cleansers and 10 gallons of water per day and that marijuana keeps him "consistent."

If Diaz arrives today and passes his drug test (results will be available Thursday), then Friday's no-show can be chalked up to a matter of poor scheduling.

However, if Diaz fails to show or the result is positive, he'll likely have an uphill battle to get back into the hunt for a title shot in Strikeforce ... or perhaps anywhere else.

Stay tuned to MMAmania.com as we will continue to update this story as it unfolds.