Just days out from the start of the AFL season the competition has been rocked by revelations that two Collingwood players have tested positive for banned, performance-enhancing substance clenbuterol.

And just a day before 34 Essendon players learn whether they will be banned for taking banned supplements, Collingwood claimed to be mystified about how two of its most highly-regarded young players returned positive drug tests.

Speaking on Fox Footy’s AFL360, coach Nathan Buckley said the club was doing all it could to support Lachlan Keeffe and Josh Thomas and to ensure the rest of organisation continued with normal duties.

The club was notified of the “devastating” news on Friday, and the pair were waiting for the results of the B sample, which were expected on April 14. The pair’s playing future remains clouded.

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“When the club received the news on Friday morning we were devastated to find out that it was in fact a positive test,” Buckley said.

“I did (talk to them) on the Friday. They’re at a complete loss as to where the positive test has come from and that’s the information we have.

Lachlan Keeffe and Josh Thomas are ‘joined at the hip’. Photo: Getty

“We’re looking for the facts as a footy club, and Josh and Lachie might have that for us.”

The drug, which helps build muscle and burn fat, is banned under the World Anti-Doping Agency Code.

The club returned to Melbourne at the weekend after attending a pre-season camp in New Zealand, where Keeffe and Thomas were roommates.

Buckley said the pair were best mates who hail from Queensland, having traveled similar paths to the elite level and, in many ways, “have been joined at the hip for their whole career”.

Although Buckley was careful to say investigations were in the early stages, the club may argue that Keeffe and Thomas innocently consumed something that contained the substance.

In 2012, Australian cyclist Michael Rogers claimed that he was the victim of a mix-up with contaminated food in China after testing positive for the same drug. He was later cleared of any wrong-doing when it was proven he ate contaminated meat.

In 2011, five Mexico football players were suspended from the Concacaf Gold Cup in Mexico after testing positive for the same substance. It was later found the players had also eaten contaminated meat.

Meanwhile, it was a positive test for clenbuterol that cost Alberto Contador his 2010 Tour de France win.

Clenbuterol is commonly used in livestock in countries such as China and Mexico to create leaner meat.

— Sam Edmund (@SammyHeraldSun) March 30, 2015

The two Collingwood young guns have not been able to tell club officials how the banned substance got into their bodies.

“That’s what you think – where did the drug come from, how did it come to be and what does this say about them as young men?” Buckley said.

Gary Pert and Nathan Buckley have a new headache. Photo: Getty

“But they’re very decent, upstanding young men, and if you’d asked me of a couple that I wouldn’t have thought would ever tested positive to anything – then they would be right up there these two boys – they’re clean skins and yet they have returned a positive sample to a banned drug.”

Buckley said the entire club would be affected by the news, but they couldn’t undo their hard work leading up to the season.

Buckley said club officials would be able to speak to the pair within 48 hours. Both Keeffe and Thomas had sought independent legal advice through the AFL Players’ Association, a move the club supported.

He said Keeffe would not have been available to play round one against the Brisbane Lions at the MCG on Saturday, however Thomas was “in the mix”.

Meanwhile, earlier on Monday Collingwood CEO Gary Pert said he was “devastated” to find out that two of the club’s players would be under the microscope for testing positive to a banned substance.

“When I found out who the two players were I must admit I was pretty devastated because we’re actually talking about two of the highest-quality young men as part of our program,” Pert said.

There has been four positive banned drug tests in the last two years within the AFL.