Battlegrounds O.N.E.: Cody McKenzie gives blood to make weight, quarterfinal match-ups set

All eight welterweight competitors met their required weights ahead of Battlegrounds MMA's one-night single-elimination tournament at Thursday's weigh-ins in Tulsa, Okla.

The only snag in the proceedings came when former UFC fighter Cody McKenzie weighed in at 172.4 pounds on his first attempt. McKenzie was granted two hours to shed the extra 1.4 pounds, and successfully did so -- albeit in an unusual fashion. According to sources close the situation, McKenzie drew a pint of blood before making the 171-pound limit on his second attempt.

Following the weigh-ins, match-ups for the tournament's opening round were determined by a lottery ball draw.

McKenzie (15-4) will collide against fellow UFC veteran Brock Larson (37-8), while Joe Ray (11-3) will meet Luigi Fiorvanti (24-11), Jesse Taylor (27-10) will meet Trey Houston (10-2), and Roan Carneiro will meet late replacement Randall Wallace (9-2).

All tournament fights are scheduled to be contested for three five-minute rounds. Elbows will not be permitted until the final match. The winner of the bracket will earn a $50,000 grand prize.

Three-time UFC title challenger Chael Sonnen and legendary WWE broadcaster Jim Ross are expected to announce the event, which will air live on pay-per-view Friday night.

UPDATE: When asked whether McKenzie's curious weight-cutting strategy could be considered unsafe, SB Nation medical expert Dr. Ali Mohamadi explained, "There's no question that among a number of weight-loss options, donating blood isn't among those typically recommended. Interestingly, the short term side effects aren't actually that severe; you can get lightheaded or faint for a few hours, but the actual volume of fluid that's taken is replenished within 24 hours.

"The real risk is with frequent blood donations. It's not recommended to give blood more than every 8 weeks or so because it takes about that long for the red blood cells that are lost to be replaced by the bone marrow. Frequent donations also can result in iron deficiency, which itself causes a decrease in hemoglobin, the molecule that transports oxygen from the lungs to the rest of the body. So while it may not be an issue immediately, it's something that can definitely become an issue if this is an option he chooses frequently."