Kyler Murray has announced on social media that he is giving up baseball and will pursue his dreams of being an NFL quarterback.
"Moving forward, I am firmly and fully committing my life to being an NFL quarterback," Murray stated in the post.
"Football has been my love and my passion my entire life. I was raised to play QB, and I very much look forward to dedicating 100% of myself to being the best QB possible and winning NFL championships."
That shuts the door on the possibility he will play for the Oakland Athletics, who made him the No.9 overall pick in last June's MLB draft.
After the draft, Murray signed with the A's and received a $4.7 million ($A6.6m) signing bonus.
According to published reports, Murray will return $1.29m ($A1.8m) of the $1.5m ($A2.1m) he received last year. He forfeits the remaining $3.16m ($A4.5m) due March 1.
Murray was granted permission to play one final year of football at Oklahoma last fall before reporting to the A's, and he won the Heisman Trophy.
Some NFL mock drafts have Murray being drafted in the first round, which would make him the first athlete drafted in the first round by both an NFL and MLB franchise, according to ESPN's Field Yates.
Murray is scheduled to attend the NFL Scouting Combine, to be held February 26-March 4 in Indianapolis.
"I have started an extensive training program to further prepare myself for upcoming NFL workouts and interviews," he said in his social media post.
"I eagerly await the opportunity to prove to NFL decision makers that I am the franchise QB in this draft."