Conor McGregor was drug-tested onboard his £3m super-yacht by USADA officials in yet another tease of a return to the UFC.
The former two-weight UFC world champion, who retired earlier this year, is currently in Monaco as he prepares for a 180km voyage to raise awareness of water safety.
McGregor will complete the challenge this weekend with Princess Charlene, a former Olympic swimmer and husband of Prince Albert II.
But on Friday the Crumlin native posted pictures on social media of a drug-testing kit and said: "What’s going on here UFC? USADA have just arrived to my yacht this morning for testing? I’ve retired guys!
"But go on then, I’ll allow them test me. It’s all natural here baby! Forever and always, God Bless. 180km across the Mediterranean Sea tomorrow! LET’S GO!!"
McGregor has allowed himself the opportunity to return to fighting by remaining gin the testing pool, which a fighter has to be in for at least six months before he can fight in the UFC.
McGregor hung up his gloves in June - for the third time in four years - after growing frustrated at a lack of viable opponents.
But the proposed return of Nick Diaz early next year prompted him to hint at a return.
And he took another shot at both Nick and his brother Nate - with whom McGregor has twice shared the Octagon - as "juice-head rats".
Another option for McGregor opened up on Thursday when Dustin Poirier was unable to agree terms with the UFC to take on Tony Ferguson in October.
The lightweight rivals were due to clash as the co-main event to Khabib Nurmagomedov vs Justin Gaethje in Abu Dhabi.
But Poirier, who has been beaten by both McGregor and Poirier, could not thrash out a deal with the UFC top brass.
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