WESTFIELD, Ind. — The first thing Andrew Luck noticed about rookie guard Quenton Nelson was his back.

He calls it the biggest he's ever seen. And he's not the only guy doing double-takes of his new, massive personal protector.

Veteran guard Matt Slauson talks about Nelson's expansive shoulders and enormous chest. Longtime left tackle Anthony Castonzo dubbed Nelson an immovable refrigerator on reporting day.

Regardless of the description, they seem apt for the newest addition to another revamped Indianapolis Colts offensive line.

"At guard, you want one of those people that if he's walking down the street and someone comes and runs at him full speed, that person is going to get knocked out," Castonzo said. "He's got that ability that when people run into him, they move, and he doesn't."

The Colts have spent years searching for someone with Nelson's punch.

Andrew Luck took more than 400 hits from 2012-16, the highest total among quarterbacks in the league, and has been sacked an astounding 156 times in 70 career starts.

All those shots finally caught up with Luck. He missed nine games with assorted injuries in 2015, made 15 starts in 2016 despite playing through shoulder pain and missed all of last season to rehab from surgery for a partially torn labrum in his throwing shoulder.

If it wasn't obvious Indy needed to invest in protecting Luck after he signed a $140 million contract extension in 2016, three consecutive seasons without a playoff appearance made the next step clear.

So the Colts went big.

They selected the 6-foot-6, 330-pound Notre Dame linemen No. 6 overall in April's draft — the first guard selected that high in more than two decades.

He has not disappointed at training camp. Nelson has already shown c he's capable of stoning more experienced defensive linemen, using his flexibility and balance to keep his body in front of pass rushers and flicking away opponents with a quick swipe of his strong hands.

"There's a reason an offensive guard was picked sixth overall," said Jack Mewhort, the Colts' former starter and a second-round pick in 2014. "Obviously, we haven't played the game yet, but from everything I've seen, he's lived up to it so far. He's the man."

The first real test comes Aug. 9 at Seattle. But Colts fans got a glimpse of what to expect when the Colts put on full pads for the first time last weekend.

In Saturday's one-on-one drills, Nelson managed to recover from the initial punch of a 305-pound defensive tackle then stood his ground and drove the defender backward.

General manager Chris Ballard and coach Frank Reich expected nothing less after watching his college tape and hearing him explain his goal would be breaking the will of an opponent.

"He just brings a lot of power, but then you've also got his young, bulldog tenacity that is a lot of fun and fun to watch," said Slauson, now in his 10th NFL season. "I don't have a lot of the athletic tools he has, but I consider myself a big-bodied guy and I like to bring kind of a nastiness myself. What I am going to try and do with him is help him grow in the game as fast as he can."

Nelson and rookie guard Braden Smith, a second-round pick, could change the whole complexion of the franchise.

With Luck signed through 2021 and centre Ryan Kelly, a first-round pick in 2016, coming back from an injury-plagued second season, Nelson and Smith could help the Colts plug what has been a leaky interior line.

"Ryan has been a big help for me," Nelson said. "He's the smartest guy in the room. He knows all of the assignments. He's been a huge help for me on and off the field."

Instead, Nelson lets his play, intensity and size speak for themselves.

"He did approach me in the hallway (Saturday) and I was a little shocked because it was the first day in pads," Reich said, laughing through his answer. "I won't get into the details of what he was saying exactly, but let's just say he was excited to be in pads."

Notes: Tuesday's practice was moved inside because of rain, but Reich said he thought the Colts reacted with energy and emotion. Longtime centre Jeff Saturday attended the workout. ... Austin Howard, who should battle for the starting right tackle job, was activated from the nonfootball injury list Tuesday. Reich said Castonzo (hamstring) and starting safety Clayton Geathers (off-season knee surgery) were "real close" to being activated from the physically unable to perform list "very soon." ... Linebacker Anthony Walker is expected to miss several weeks after injuring his groin during Sunday night's practice.

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