One of the UFC middleweight division’s top contenders Yoel Romero has been notified by USADA of a potential anti-doping violation following an out-of-competition drug test.

““The UFC organization was notified today that the U.S. Anti-Doping Agency (USADA) informed Yoel Romero of a potential Anti-Doping Policy violation stemming from an out-of-competition sample collection,” a UFC statement reported. “USADA, the independent administrator of the UFC Anti-Doping Policy, will handle the results management and appropriate adjudication of this case involving Romero.

“Additional information will be provided at the appropriate time as the process moves forward.”

The 38 year-old ‘Soldier Of God’ narrowly defeated Ronaldo ‘Jacare’ Souza by split decision at UFC 194 in December in what was believed at the time to be a No.1 contender bout.

That was Romero’s seventh win in a row since joining the UFC in April of 2013 and despite not being his most convincing win current champion Luke Rockhold had confirmed that it was likely that the first defense of his title would come against either Romero or an immediate rematch with Chris Weidman.

With Romero now likely to face a lengthy suspension due to the UFC’s strict anti-doping policy which came into effect in July of 2015, the latter option now looks like the most likely.

At this stage it’s not clear what illegal drug USADA believes Romero took, though respected MMA reporter Steve Marrocco (MMAJunkie / USA Today) wrote on Twitter that he was hearing that, “Romero popped for a designer steroid – a peptide that increases testosterone production.”

If it does end up being some kind of steroid then Romero looks to be facing a two year ban if found guilty in addition to his fight with ‘Jacare’ being amended to a no-contest.

Upon hearing the news last night, ‘Jacare’ Souza’s manager stated that, “with doping or not, Jacare won that fight,” and called for a title shot with Rockhold.

Romero is the most significant fighter to have been caught using performance enhancing drugs so far since the UFC’s new drug testing procedures began. You could argue that Mirko ‘Cro Cop Filipovic, who was recently suspended for two years for using HGH, is a bigger name, but he was very much at the tail-end of his career and wasn’t in the title picture. By the same measure, Gleison Tibau, who was reported to have tested positive for EPO last month, has been in the UFC longer, but has never been a serious title contender.

Romero being taken out of the picture will have a much bigger impact on his division than either of the other two, and this is unlikely to be the last big star that finds himself facing a lengthy suspension from the sport in 2016 with MMAfighting and FOX Sports reporter Ariel Helwani confirming last night that USADA’s drug testing only began operating in “full effect” from January 1st after a gradual ramping up over the previous six months.