Lawrence Okoye has said that he is learning "as quickly as possible" as he takes part in his first training camp with the San Francisco 49ers.
The British discus record holder joined the Super Bowl runners-up as an undrafted free agent last month, despite having never played a down.
The 21-year-old told the Sacramento Bee: "I got a couple calls wrong but it's all part of the learning process. As it went on, I got more and more comfortable. When we went up against the O-line, it got a bit more difficult but I adjusted.
"That's what's going to keep happening. I'm going to go up and down, up and down, as I carry on learning how to play this position, how to play this sport.
"I'm just trying to learn as much as possible, as quickly as possible. They're being great with me. They're not going to force feed me. There's a lot of prep we have to do in the classroom before we get on the pitch, or the field, or whatever you guys call it."
Okoye is being groomed as a defensive end, having impressed scouts with his speed and strength at the Super Regional Combine earlier this year.