KNOXVILLE, Tenn. (AP) — Tennessee's Jauan Jennings says he wasn't even thinking about the possibility of cracking the starting lineup for the season opener when he moved from quarterback to wide receiver last month.

Now he is on top of the depth chart as the 25th-ranked Volunteers prepare for Saturday's game against Bowling Green at Nashville's Nissan Stadium, about a 45-minute drive from Jennings' hometown of Murfreesboro. Not bad for someone who says his experience at receiver before last month was limited to backyard games with his brothers.

The 6-foot-4 freshman said he is a little surprised by his rapid rise.

"But me (having) played quarterback, I kind of knew the playbook," he said. I just had to learn the techniques. ... Great teammates just help you a lot with that."

Jennings was one of three quarterback prospects to sign with Tennessee in the 2015 recruiting class, and he worked out with the Vols at quarterback during spring practice. But he also knew he wouldn't play right away unless he switched positions.

Junior Joshua Dobbs already had cemented his status as Tennessee's starting quarterback. Jennings wasn't as polished a passer as freshman Quinten Dormady, who has since been named Dobbs' top backup. Jennings welcomed the possibility of catching passes instead of throwing them.

"His mentality's what sets him apart," wide receivers coach Zach Azzanni said. "Some guys have that mentality where they don't quit, they don't stop, they just keep coming back. He's ultra-competitive, and that's what's propelled him to that spot."

Jennings credits his family for fostering that attitude. Jennings said he and his siblings would compete at everything from playing football to seeing who could wake up and get to the breakfast table first.

"It's been like that since I was growing up and being a little kid," Jennings said. "My dad, we always talk about how he won a state championship in football and I didn't. It's just instilled in me. It's always been in my family. That's the only way to live life is what I've been taught, (that) you've just got to be competitive.

"Nothing's going to be given to you. You've got to earn it."

Jennings' emergence has boosted a receiving corps that had a rough preseason.

Alton "Pig" Howard was suspended for the season opener due to a violation of team rules. Jason Croom and Vincent Perry underwent arthroscopic knee surgery, knocking Perry out for the season and sidelining Croom for at least a few more weeks. Preston Williams wasn't cleared by the NCAA until Friday.

Tennessee needed someone to pick up the slack, and Jennings was happy to oblige. Teammates believe his background as a quarterback has helped him.

"He's been dynamic," Dobbs said. "I think the best thing he did was come in early (for spring practice), especially at the quarterback position, because now when he's at receiver, he understands timing, he understands spacing, he understands where he needs to be and how he gets open."

Jennings isn't the only preseason surprise for Tennessee. Colton Jumper, a sophomore walk-on, is listed as Tennessee's first-team middle linebacker after winning a six-man competition for the job.

"He's really shown a level of consistency we're looking for at the Mike linebacker position," defensive coordinator John Jancek said. "He's really gotten better each and every single day he's been out on the field."

The walk-on's emergence is no surprise to linebacker Jalen Reeves-Maybin, the Vols' top returning tackler. Reeves-Maybin said he noticed Jumper's potential while watching him play at Baylor School in Chattanooga.

"(With) him being a walk-on, he's got to fight that much harder than everyone else," Reeves-Maybin said. "He's been through a lot more stuff than anyone has gone through, and for him to be put in a starting position at Mike linebacker is a big step for him."