STANFORD, Calif. (AP) — Trent Murphy has never been intimidated by larger linemen. After wrestling 800-pound cattle as a kid, another human just isn't that imposing.

At 6-foot-6 and 261 pounds, no challenge has ever seemed too much for Murphy's muscle. Stanford's versatile linebacker, once thought too slender for his sport, has grown into a possible first-round pick in next May's NFL draft by making up for any shortcomings in his size with his willpower.

Even after racking up accolades and rising up recruiting rankings in high school, some coaches questioned whether Murphy was big enough to play defensive end or fast enough to play linebacker in major college football. His length and demeanor still had them all visiting his home in Mesa, Ariz.

Stanford coach David Shaw, an offensive coordinator under Jim Harbaugh at the time, said the staff was sold on Murphy from the moment they watched him on video playing for Brophy College Preparatory in Phoenix.

"I don't know that we've seen a guy that played meaner in high school," Shaw said. "He didn't just tackle guys, he tried to hurt them. He tried to really get after them. Sometimes you have to teach kids coming out of high school to (be that aggressive) in college. But to see a guy like Trent in high school, we said, 'That's what we're looking for. No question about it. We don't care who else is recruiting him. We don't care what anybody else says.'"

Murphy's decision came down to a pair of Pac-12 programs: Stanford and Arizona State, which was about a "five-minute drive" from Murphy's house and also where his sister, Kayli, played basketball.

Harbaugh convinced Murphy he'd fit perfectly as a pass-rushing outside linebacker in Stanford's 3-4 defense. In the end, Murphy said it was no contest between the schools because of the way "Harbaugh handled himself and his passion for this place and what he promised we would do."

Now Arizona State is just another team standing in the way of Murphy and the fifth-ranked Cardinal (2-0), who host the No. 23 Sun Devils (2-0) on Saturday. While he spurned his hometown school for The Farm, Murphy's mental makeup can be traced back to his childhood in the Valley of the Sun.

He got involved in team roping with his father, Jerry, when he was in middle school. The family owned horses and also had a steer calf Murphy would play with "just for fun."

Once during a break from Stanford his freshman year, Murphy jumped into the pen with the fully grown steer. He quickly found himself in the fight of his life — perhaps even for his life.

"I grabbed his horns, and he started getting playful," Murphy said, recalling the story last year. "Then he started getting territorial. We got into this pushing match where I'm grabbing its horns and it's trying to drive me back and probably run me over. I gave it a tug back, and it went up on his hind legs. I just turned around and booked it and went over the fence."

Murphy, who once had ideas about being a rodeo clown, is likely headed for an NFL career now.

He led Stanford with 10 sacks and 18 tackles for loss last season along with a memorable interception returned 40 yards for a touchdown at Washington. He already has two sacks and three tackles for loss this season, with his hard-hitting ways always energizing teammates.

"He'll not only do his job, but do it at a high and punishing level," defensive end Josh Mauro said.

Murphy's abilities didn't come naturally. No matter how much he ate or how much he lifted, Murphy struggled to gain weight and grow the muscle mass needed for football.

He credits Stanford performance director Shannon Turley for building a personal nutrition plan, making Murphy record everything he eats and check his weight twice a week.

"I still have to eat a ton to maintain my weight," Murphy said, including "2,000-calorie smoothies" filled with protein-packed peanut butter, fruit and yogurt.

Murphy's growth on the field could've taken him to the NFL already. Instead, after he submitted paperwork to the league to see where he projected in last April's draft, he chose to return to the defending Pac-12 champions to improve his position and make a run at a BCS title this season.

"All the guys I came in with were coming back for a fifth year. So it was a like, 'All right, let's all come back and have one more great season,'" he said.

Murphy took part in the graduation ceremony in June and will leave Stanford with a bachelor's degree in science, technology and society. He also added a minor in political science this summer and his only requirement in the fall quarter is Spanish 3, likely the last class he'll take before professional football calls.

"I'll go back one day and maybe pick up rodeo clowning," Murphy joked. "We'll see how that goes."