NFL draft prospect Kyler Murray said notifying the Oakland Athletics about his decision to turn down the MLB for a career in American football "was tough".
Murray was the Athletics' first-round pick in the 2018 MLB Draft, however, he has opted to commit himself to the NFL.
The 21-year-old quarterback was due to report to spring training with the Athletics earlier this month before switching his focus.
Murray said it was "obviously hard" telling the Athletics he would be committing to football.
"For me, it was something I've known for a while," Murray said on Saturday. "That organisation, being with the A's, was the best possible situation for me just because they were so great throughout the football season, kind of leaving me alone and letting me do my own thing, and at the same time letting me know how much I meant to them and that type of stuff. Telling them was tough."
Despite Murray's decision, the Athletics have retained the Heisman Trophy winner's baseball rights.
"I mean, they can hold out all the hope if they want to," Murray added. "I'm going to play football."
The Arizona Cardinals have the first pick in the draft and have their eyes on Murray. If he is selected in the first round, he will be the first athlete to be drafted in the first round of both sports.
"The night I got drafted to the A's – obviously it was a great day of my life – but I've been a football player my whole life," Murray said. "I didn't know how the NFL felt about me before this season because I hadn't played.
"Going into this [football] season, [the goal] was to put myself in the best position possible. Obviously, when you win, good things happen. A lot of good stuff happened this year."
In his first season as the Oklahoma Sooners' starting QB, Murray led the team to the College Football playoff.
He passed for 4,361 yards and 42 touchdowns with just seven interceptions. He also rushed for 1,001 yards and 12 touchdowns.