England have turned to mixed martial arts in search of new techniques that will aid their quest to become the sport's number one team.
The reigning champions open their Grand Slam defence against France at Twickenham on February 4 armed with insight into wrestling, ju-jitsu and judo gleaned by defence coach Paul Gustard.
Gustard has been practising with an MMA expert based near England's Surrey training camp and believes some of the skills he has learned in the octagon will assist Eddie Jones' men throughout the RBS 6 Nations.
"It's about improving certain aspects around the contact area, around the maul and about getting back to your feet post-tackle," Gustard said.
"It's those sorts of skills that are innate in wrestling or a one-on-one combat sport and there are lots of things we can take from it.
"You always have to put it into the context of rugby, but it's helpful to see how their bodies move and how they manipulate parts of the body to get out of contact.
"You see some things that you know won't transfer and there are some that make you think how can we develop that, how can we explore that?
"It's not just the tackle but also the system. Trying drills and trying games that I think might work and might illicit a certain response from the players or get a certain outcome.
"We have four assistant coaches with England, so we then debate it and see if we can go with it."
World Rugby's crackdown on dangerous tackling has led to a flurry of yellow and red cards, resulting in uncertainty over the tackle, but Gustard insists England have been seeking to hone their technique before referees were instructed to get tough.
"What has changed now is the sanction which is more punitive. The law is the same. You have never been allowed to tackle round the head," Gustard said.
"What we want to instil in the players is good technique that can withstand duress, fatigue, pressure, the environment of a Test match.
"We have four or five key principles and then we have to expose the players to contextual situations so that they can adapt.
"Post-summer, I identified that an area of improvement could be around the tackle.
"We got physically controlled on occasion by Australia during the summer, particularly in the third Test, and we wanted to be able to control the pace of the gain line."
Gustard denies England's training secrets could be compromised after his fellow defence specialist Jason Ryles worked with the squad before the autumn.
Ryles was seconded from Australian rugby league club Melbourne Storm, who also have an arrangement with the All Blacks which dates back to 2010.
When asked about potential leaks, Gustard said: "I would say unequivocally not. You're talking about someone's coaching integrity there. You never question someone's integrity."
Gustard confirmed that George Kruis would recover from his fractured cheekbone in time to face France, while prop Joe Marler remains in contention as he rehabilitates a fractured leg.