"I want to let you know that I just signed the contract with VADA for year round testing," Alvarez wrote on Twitter.

It is a move that could go a long way to helping restore the Mexican star's tattered reputation and one that clears a major hurdle to putting the much-anticipated rematch with unified middleweight world champion Gennady Golovkin back together for Sept. 15.

"We have received paperwork from Mr. Alvarez's representatives for year-round testing (24/7/365) through VADA," Dr. Margaret Goodman, president of VADA, said in an email to ESPN.

Alvarez twice tested positive for the performance-enhancing drug clenbuterol in February in VADA tests, forcing the rematch with Golovkin scheduled for May 5 -- and worth tens of millions of dollars to both fighters -- to be canceled.

Alvarez, who got a controversial draw against GGG when they met last September, was subsequently suspended for six months on April 18 by the Nevada State Athletic Commission.

Alvarez is eligible to be reinstated in mid-August, six months from the date of the original positive test.

Alvarez (49-1-2, 34 KOs) was also dropped in recent days from the WBC's rankings as its No. 1 middleweight contender for his failure to enroll in the mandatory Clean Boxing Program that all of the organization's titleholders and top contenders must be in.

Alvarez's decision to not enroll immediately in a testing program as soon as he was suspended stoked outrage from fans and media and left many in the boxing industry dumbfounded as to why if Alvarez so strongly professed to be a clean fighter -- he blamed the positive tests on contaminated Mexican beef -- he would not embrace a rigorous out-of-competition testing program.

Now he has, and his promoter, Golden Boy CEO Oscar De La Hoya, said he is relieved that Alvarez made that decision.

"This is good news," De La Hoya told ESPN. "This is voluntary and Canelo is paying for the testing out of his own pocket because he wants to prove to his fans that he is a clean fighter. Any time they want to test him he will make himself available. ... Canelo is doing this because he is listening to his fans. The criticism will always be there, but he decided to listen and prove to everyone that he is clean."

Coincidentally, the Nevada State Athletic Commission sent its own drug tester to Alvarez's hometown of Guadalajara, Mexico, to test him on Monday -- taking blood and urine for the first time since he was suspended -- once the commission determined it was within its rights to test him. Alvarez was cooperative, according to De La Hoya. The test results won't be available for approximately five days.

"What people don't know is Canelo is getting randomly tested by the Nevada commission," De La Hoya said. "He wants to be tested year-round. He wants to do this for his fans and that's why he's doing this so they won't doubt him."

Golovkin (38-0-1, 34 KOs) faced late substitute Vanes Martirosyan on May 5 at the StubHub Center in Carson, California, and demolished him in two rounds to retain his 160-pound world title for a division record-tying 20th consecutive time.

Before the fight, GGG and his trainer, Abel Sanchez, continued to be extremely critical of Alvarez because he was not being tested at the time. They said Alvarez's enrollment in a testing program was a requirement to even discuss a new deal for the rematch, one in which Golovkin is now seeking a bigger slice of the financial pie.

De La Hoya and Golovkin promoter Tom Loeffler both said Canelo's enrollment will be beneficial to finalizing the rematch.

"We've started discussions with Tom. We want to make the fight happen and this is another step in the right direction," De La Hoya said. "Every top fighter should be tested by VADA on a year-round basis. That's the only way to clean up the sport.

"Hopefully, we can make the fight. ... These guys, Canelo and GGG, sure don't like each other now. If the fight happens in September it will be that much better of a fight. Now there really is bad blood. It will be a hell of a fight if it happens in September, but regardless Canelo will be fighting in September.

"This is a huge step, a major hurdle we have cleared. There are no excuses whatsoever. GGG wants the fight, Canelo wants this fight, so let's just get past this and move forward and give the fans the fight they want to see again."

Said Loeffler: "I think it's important for Canelo to be enrolled and that was one of the requirements in the discussions we've had with Golden Boy for the rematch. They never balked at it. It's one less hurdle. I'm in continued discussions with (Golden Boy president) Eric (Gomez) and hopefully we have some resolution here in the near future."

Before the fight with Martirosyan, Golovkin, a strong testing advocate, said he would re-enroll in VADA to continue out-of-competition testing. "I contacted VADA to re-enroll him and continue the testing he was doing for the fight on May 5," Loeffler said.

"It hasn't started yet but I'd imagine it will by next week. With regard to Canelo, I was a little bit surprised that for someone proclaiming his innocence so strongly he wasn't testing. But it's good to see him enrolled. It helps his image tremendously and this is something GGG and Abel have always wanted to have -- a level playing field for both guys.

"We felt both guys should test continuously leading up to the (rematch). For the last fight the testing started three months before the fight and since Gennady is an advocate for this testing he wanted to lead the way for the continued testing. I think a lot of fighters can slip through loopholes by the testing starting too close to the fight and then it doesn't matter."