LINCOLN, Neb. (AP) Nebraska safety Nate Gerry was ejected from back-to-back games last season because officials ruled he targeted receivers above the shoulders when tackling them.

This year, Gerry and his teammates are transitioning to a tackling method whose objectives are to eliminate dangerous helmet-to-helmet contact while making defenders dominant tacklers.

Nebraska is the latest program to adopt rugby-style tackling. As in rugby, where players wear no helmets, the tackle is made by driving a shoulder into or near the ball-carrier's hip, wrapping him up and taking him to the ground. Though the hip is the ideal target, it could be anywhere between the knees and armpit. All the while the defender's head remains to the side of the ball-carrier's body, away from the tackle contact zone.

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In a sport beleaguered by concussion concerns, rugby-style has been touted as a safer way to tackle, and teams can practice it with or without helmets and pads.

Traditionally, defenders in football have been instructed to put their heads across the body of the ball-carrier to stop forward momentum.

''It takes a while for us to get the basics down to where it comes to muscle memory,'' Gerry said. ''The science behind it, the explosion of power and using your hips more ... I like it. It's supposed to be just as violent but safer than what we've been learning.''

Seattle Seahawks coach Pete Carroll was among the first to promote rugby tackling in football. He and assistant Rocky Seto worked with rugby great Waisale Serevi to develop what became known as the ''Hawk Tackle,'' the technique that's subject of a popular 2014 video that circulated through coaching circles and was updated last year .

Serevi's Seattle-based company, Atavus, was founded in 2010 to promote and develop the growth of rugby in the U.S. It added a football division in 2015 to partner with college, high school and youth programs to teach rugby tackling.

Nebraska joined Ohio State, Washington and Rutgers as Atavus college clients. Nebraska is paying $100,000 in 2016 and $80,000 in 2017. Atavus is providing 400 hours a year of services, including the training of coaches, designing drills, detailed analyses of tackling execution in practice and games, and access to an online portal where staff can obtain reports and other materials.

Neuropsychologist Art Maerlender, a concussion specialist and associate director for Nebraska's Center for Brain, Biology and Behavior, said keeping the head to the side when tackling is a ''no-brainer.'' A former rugby player and coach, Maerlender said he told a Nebraska athletic administrator about Atavus. Football coach Mike Riley already knew about rugby tackling from watching Carroll's video. The Huskers signed on and began implementing the technique during spring practice.

Riley said he saw effective rugby tackling in the spring game.

''Not every situation is perfect,'' he said. ''Sometimes tackles are ugly because you just have to get them down. The only way you can change old habits is tons of repetition. Yes, there'll probably be guys who revert. In the end, one of the main goals is to keep the head out.

''I think they are embracing it. When you tell players the two words `safer' and `better,' they'll buy into it.''

Erik Swartz, a kinesiology professor at the University of New Hampshire, said more research is required before rugby tackling can be definitively deemed safer at all levels of football. Variables such as a player's physical and mental maturity, experience, expertise of his coach and nature of prescribed drills could affect the player's ability to control his body while making a tackle.

But Swartz has seen encouraging signs. For two years, he has studied how performing tackling drills without a helmet affects a player's behavior when that player puts on his helmet in contact practices and games. He had 25 players on the New Hampshire football team go helmetless during tackling drills and 25 others go through normal football activity.

In 2014, among the players who were helmetless for tackle drills, there was a 28 percent decrease in head impacts in full-squad contact practices and games from the start of the season to the end. Compared with the control group that same season, the helmetless group had 30 percent fewer head impacts. Results have not been published for the 2015 season, Swartz said.

Last year he began a similar two-year study involving four high schools in New Hampshire.

''Inevitably, if you decrease head impacts, that decreases your risk for concussion, right?'' Swartz said. ''But until we have a larger sample size with the high school study we're currently doing ... we're not saying we're reducing concussions until we can actually demonstrate through research that we have done that.''

Atavus president Ron Lloyd said football carries an inherent injury risk but that ''anecdotal input'' from client coaches has indicated fewer head injuries.

USA Football, the sport's governing body for amateur players, began teaching a below-the-waist tackling technique for the first time as part of its 2016 high school coach certification program.

''It's a skill and technique that coaches have success with,'' said Andy Ryland, senior manager of education and training. ''Not every coach teaches it, not every coach believes in it. We felt it was something we needed to teach our constituents as a technique that is in the market and, if our coaches want to do it, we'll provide them best information out there on how to teach that technique.''

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AP college football website: http://collegefootball.ap.org