When Rory MacDonald entered round 5 of a pulsating, thrilling welterweight title fight with then-champion Robbie Lawler at UFC 189, he was unanimously up 39-37 on all three judges' scorecards. MacDonald would last exactly 1 minute before Lawler dropped him for the come-from-behind TKO.

It's been 13 months since MacDonald's lone shot at a UFC belt ended in devastating defeat, and while Lawler is no longer the champion, MacDonald is no longer with the UFC. The 27-year-old Canadian opted to sign with Bellator MMA in free agency, a move which was formally announced on last Friday's Bellator 160 card.

During MacDonald's appearance on The MMA Hour on Monday, he brought up Lawler's UFC 189 drug test results, implying that Lawler may not have been fighting "clean" in their fight.

"Actually right before this conversation, something very interesting came up to me. We are going to have to see where it goes, but it has something to do with the title fight against Robbie Lawler. Some very interesting information just came about. We'll see what happens with that. I don't really want to speak too loud about it, but it's something that really grabbed my attention and I think a lot of people are going to be very interested to hear about this if it actually is true, I have to do my research. But it could be a potentially very big thing and it pisses me off. It pisses me right off to hear about it, to be honest. I feel very robbed.

"I worked hard for that fight and I fought my heart out. I left everything in there. I left my soul and I really left everything out there. I came in honest, and I always have my entire career. I don't play with any dirty drugs, any performance enhancers or something I don't believe in morally. I always believe in myself that if I work hard, work on my techniques, train hard that I can get to the top and be the best. The fact that whatever happened in there, if this is true, it pisses me right off to my core. Some test results came out four times higher than the limit for my fight with him. It could be bullsh*t. That's why we have to look into it. I don't want to start pointing fingers or anything. Look at that team's history. It makes me very suspicious but I can't go out and start saying for sure without making my research that all this is true."

Lawler has never failed a drug test in his entire MMA career. UFC 189 was one of the first events -- in fact, it was the first UFC pay-per-view -- to be held under the USADA drug testing partnership. MacDonald could be questioning this test result (H/T Dimspace), which showed high levels of Luteinizing Hormone (LH). It should be noted that this test was administered in June by the Nevada Athletic Commission and not USADA.

Bloody Elbow's Iain Kidd will have in-depth analysis of Lawler's drug test results later today.

(Transcription via MMA Mania)

(Video of his interview can be seen at the top of the page at the 1:51:00 timestamp)