Anthony Harris spent most of his football playing days hearing he’s not strong enough to compete at the highest level.

Underneath the No. 41 jersey and bulky pads of the Vikings’ rookie safety is a thin 192 pounds. Lack of size was arguably what kept him from being taken in the NFL draft in May. However, the Vikings had someone on the inside feeding them a different story, and that led to the undrafted free agent’s first NFL start last week.

Harris might not be built like 6-2, 214-pound safety Harrison Smith, but for several years he had been proving to Vikings strength and conditioning coach Evan Marcus that he was capable of building the strength necessary to succeed in the NFL.

Marcus spent time with Harris at the University of Virginia before being hired by the Vikings in 2014.

“People kind of look at my frame a little bit and may underestimate me,” Harris said. “Ever since I stepped in at the University of Virginia, I always wanted to be one of those guys that wanted to get better not only on the field and making plays but in the weight room, as well. Just showing [Marcus] I was a competitor, trying to be in the top tier of the different lifts that we had, being able to do that I think showed him that I do have dedication and the hard work.”

Harris, 24, has gained 9 pounds since signing with the Vikings. He was one of the team’s final cuts before going on the practice squad in September, and finally got a chance against Arizona last Thursday when Smith and strong safety Andrew Sendejo were sidelined, and backup Antone Exum was lost for the season, because of injuries. Harris had a team-high eight tackles and one pass defended in his first NFL game, playing all 67 defensive snaps just two days after his promotion from the practice squad.

“I would have liked to get out there a little bit sooner, but it’s all about waiting your turn and being ready,” Harris said. “I’m just glad I stayed focused and when my number was called, the preparation I put in to that point paid off and I was ready.”

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In mid-October, while the Vikings were sorting through who would line up next to Smith, Vikings coach Mike Zimmer said Harris was the safety closest to earning playing time on Sundays, labeling him as smart and athletic.

Nearly two months passed and it took injuries to all four of the Vikings safeties on the 53-man roster for Harris to get his chance. And after one game Zimmer still holds the same sentiments for the undrafted rookie.

“First time out, the game didn’t seem too big for him,” Zimmer said. “He made some plays … He made some good tackles in the ballgame.

“The good thing for him is he’s a very smart kid. He understands concepts and understands things. … He wasn’t perfect by any stretch of the imagination, but he did some natural things out there.”

But Zimmer isn’t ready to give Harris the regular starting job just yet.

“Maybe [he’s the long-term solution]. Everybody wants to jump the gun on these one-game things,” Zimmer said. “After the first week Exum was the savior, now [Harris]. It’s about over the course of time. Let’s finish out these games and figure out how he does and we’ll evaluate more.”

Harris, who is 6-1, has become known for his study habits, his ability to learn quickly from those around him, and his effort on the practice squad.

“You look at him and Diggsy [rookie wide receiver Stefon Diggs],” said defensive backs coach Jerry Gray. “Those guys understand scout team, some guys don’t, that this is my meal ticket to go out and play and if I get a chance I’m going to go play well.

“When [Marcus] vouched for him, you say, ‘Hey, this is a good kid and he understands what he’s supposed to do. He’s going to take responsibility.’ … A lot of guys don’t get that in college.”

Harris didn’t back down from Arizona standout 6-3, 218-pound wide receiver Larry Fitzgerald and he won’t back down from proving people wrong in the weight room. Harris said he squats nearly 500 pounds.

“Guys that have never really seen me lift or do things like that, I think they’d be surprised if they looked over and saw how much I had on the bar,” he said.

Smith joked that he didn’t believe it before adding, “He’s too skinny for that.”

What Smith does know now, though, is that Harris can compete in Zimmer’s defensive scheme and against some of the league’s top receivers.

“He played awesome,” Smith said. “Couldn’t really ask for much more. He made the plays that came his way, he tackled really well. … There are a lot of things to be excited about with Anthony.”