EAGAN, Minn. -- A bad string of luck sidelined Rashod Hill for days at a time during training camp. First it was an illness that caused him to lose eight pounds and kept him out most of the first week. During Minnesota's first practice after a preseason win in Denver, Hill stepped on the foot of the guard next to him during 11-on-11 and rolled his ankle.

Every time Hill has gone down, Minnesota Vikings second-round rookie tackle Brian O'Neill has been thrust into the mix with the first-team offensive line. It's unlikely Hill will play against Jacksonville on Saturday after missing three days of practice, meaning O'Neill should fill the void at right tackle once again.

This was hardly the expected projection for O'Neill's introduction to the NFL when he was drafted four months ago. Given the likelihood then that Mike Remmers would remain inside at right guard, Hill was the defacto starter at right tackle with the expectation that O'Neill would need time to develop his body and the physical tools required to play tackle in the NFL.

Brian O'Neill making a push for a starting job is no longer an extreme long shot. Jim Mone/AP Photo

Fast forward to mid-August, the Vikings have expedited that process with O'Neill out of necessity. On top of Hill, injuries have thinned out the offensive line with left guard Nick Easton out for the year, post-neck surgery, Pat Elflein still on the PUP list and Remmers yet to go through a team period after recovering from an ankle injury.

The Vikings were still shuffling around as late as Thursday. Tom Compton left practice because of an apparent arm injury that pushed Danny Isidora over to left guard and moved O'Neill inside to right guard while Aviante Collins took over at right tackle.

What O'Neill has encountered during the past three weeks has forced him to fast track himself, getting past the mental hurdles that come with losing battles against players with far more experience and learning how to grow from those reps.

"Coming in, that's one of the first five things Pat Elflein ever told me," O'Neill said. "I was talking to him about the biggest differences. He said, 'You probably didn't get beat in college, especially in practice.' My biggest thing here was, I'm going to get beat, but in camp, that's the place for it. Take it, learn from it and get better from it. You're still going to get beat again tomorrow and the next day, but being able to take that, realize that he's not just beating you, he's beating other guys too."

The 6-foot-6 tackle is only in his fourth year playing on the offensive line, having transitioned from blocking tight end at Pitt ahead of the 2015 season to right tackle, where he put on 35 pounds in a six-week span.

He has followed a similar plan in Minnesota, consuming around 6,000 calories daily to maintain weight above 300 pounds.

His outing in Denver featured a total of 47 snaps with 23 of those dedicated to pass-blocking. O'Neill was given a "clean" grade by Pro Football Focus in his first NFL action, and though he has an uphill battle ahead of him, where he is now is a far cry from where he was when he arrived for rookie minicamp.

"That was a process for him," coach Mike Zimmer said. "I think it's really starting to help. He's had a couple really good days of practice on some of the things he was doing in the rookie camp that we've been trying to correct. To me, that has shown a lot of improvement. He still has a ways to go on some of the things. He is really, really good at getting in the second level in the running game. Obviously, there are some other things he has to work at. I've been impressed with how he has improved in some of the pass protection things, from what he was doing in OTAs."

O'Neill's transition has been an up-and-down process of getting through the steep learning curve at tackle. The reps he took against Danielle Hunter and Brian Robison when he split time at right tackle when Hill was healthy delivered some perspective. By the time he faced Calais Campbell one-on-one and helped on double teams of Malik Jackson when the Jaguars were in town for joint practices, O'Neill could walk away knowing that he experienced growth in that period, regardless of how many reps he won and the number he didn't.

Training camp allows O'Neill to view his progress in a vacuum. He's better than where he was at the end of July, but he still has a long way to go before he's ready to face elite pass-rushers in a real game. On Sept. 9, whomever is playing right tackle will expect to go head-to-head with DeForest Buckner, Arik Armstead and Solomon Thomas. It doesn't get any easier from there on out with with trips to Green Bay, Los Angeles (Rams) and Philadelphia within the first five weeks of the season.

The progress O'Neill has made puts him at a point where making a push for a starting job is no longer an extreme long shot. Depending upon what happens during the next three preseason games and when Hill comes back, O'Neill might show he's further along and prove himself as the Vikings' strongest option at right tackle.