Featherweight fighter Chad Mendes, left, must be separated from Conor McGregor by UFC President Dana White after a weigh-in last year. (LE Baskow/Las Vegas Sun, via AP)

For the third time in two weeks, a UFC star is making headlines for performance-enhancing drugs. But while Jon Jones and Brock Lesnar continue to appeal the results of their respective failed tests, Chad Mendes is accepting his punishment — a mandatory two-year suspension, announced by the U.S. Anti-Doping Agency on Wednesday, for taking GHRP-6, a growth hormone.

“I didn’t do my homework and that was a big mistake,” Mendes said on Twitter after learning his test came back positive. “I own it and I’m going to pay for it.”

Mendes (17-4 MMA, 8-4 UFC), who unsuccessfully challenged Conor McGregor for the interim featherweight title last year, tested positive for the substance in an out-of-competition test on May 17, the USADA said. Under UFC’s anti-doping policy, fighters are required to submit to random tests throughout the year, whether they’re competing or not.

Mendes, 31, will be eligible to fight again on June 10, 2018.

Meanwhile, USADA is still adjudicating tests from the light heavyweight contender Jones and returned heavyweight Lesnar, both of whom failed tests around the much-anticipated UFC 200 event.

News of Jones’s failed test broke just three days before the July 9 fight, causing UFC boss Dana White to replace him last-minute with Anderson Silva, who ultimately lost to Daniel Cormier in a non-title match.

Lesnar, for his part, fought and beat Mark Hunt at UFC 200 to take home a purported $2.5 million purse. It was only days later, however, that news broke that he had also failed two drug tests.

The UFC has provisionally suspended Jones, who had metabolites for estrogen blockers in his system, while the mixed martial arts promotion waits for USADA to confirm the results. Lesnar has yet to suffer any sanctions. Neither the promotion nor USADA has announced what PEDs were found in his system.