College football star and NFL prospect Randy Gregory is opening up about his struggles with marijuana after testing positive for the drug, but is placing the blame squarely on himself.

Gregory tested positive for marijuana at the NFL Scouting Combine last month, but only revealed this to reporters on Wednesday. He only learned of the failed test two weeks ago, but admitted it came in a humiliating fashion during a phone call with his father, who opened a letter from the NFL thinking it was an invitation to attend the draft. Instead, the note informed him of the failed drug test.

“I blame myself ... there’s really no else I can blame,” said Gregory. “Am I worried? Yeah, I’m worried. At the same time, I’m confident. I know I’m going to be all right in the end.”

The pass-rusher said he first smoked marijuana after graduating high school and used it to cope with anxiety after failing to qualify academically for Purdue University. His pot use quickly became a problem during his college career after testing positive for marijuana twice last year at the University of Nebraska, and being threatened with a permanent ban from the team if he failed a test again.

Gregory has insisted that he hasn’t smoked since December, but still recorded a positive test due to his THC levels being elevated from previous use. He also denied using any other illegal substances and told reporters that he is now taking regular drug tests.

"I don't wake up every day saying, 'I'd really love to go smoke,'" said Gregory. "It's not a struggle for me every day (now), it really isn't. In the past, hell yeah, it's been a struggle. Now, I'm focused on my dream."

Some of the major players in the NFL are less convinced, though. Executives from two NFL teams told NFL Media that they had reservations of drafting Gregory due to his off-the-field “issues.” Even worse, those comments were made before his failed drug test was revealed.

Last September, the NFL unveiled its revised drug policy, which increased the threshold for a positive marijuana test from 15 nanograms per milliliter of urine to 35 ng/ml.