The rugby scrum! Fun to watch. Impossible to understand. We break down how it works and ask pros how it feels inside the tendon-tearing battle of wills. Answer? Grabby!
How it works
1. To restart play, eight players from each team line up in three rows facing each other.
2. The players squat (crouch!), grab on to their opposition (bind!), then start pushing forward (set!).
3. The offensive scrum-half rolls the ball into the middle of the scrum.
4. The offensive hooker, at the center of the front row, tries to win possession with his foot. He's joined in front by two props, buttressed by two more rows.
5. The offense's goal is to win the ball and launch a play. The defense's job is to halt the pile and/or drive the offensive scrum back far enough that the defense can claim the ball.
How it feels
"It is heaven and hell at once. The heaven is the pure, physical, one-on-one battle with your opposite number. The hell is the difficulty breathing. And the smell." -- George Chuter, ex-England hooker
"Scrums have changed. It used to be you'd get rammed into the floor. Your forehead or nose went straight into the deck. But with the engage more controlled [the rules have changed slightly], it's rare you get the scrum collapsing. Now it's just elbows getting tangled up." -- Dan Cole, England prop
"Scrummaging was put simply to me by a coach: 'If you're not uncomfortable, then you're doing it wrong.'" -- James Horwill, ex-Australia captain and second-row
"When a scrum violently hit the deck, my default consideration was always paralysis. I would take a millisecond to ensure I was intact, then I'd relax and breathe knowing that it would eventually unfurl and we'd go again. For going again, I'd need all my energy. So wiggle those fingers and toes, then catch your breath." -- David Flatman, ex-England prop
"It's a battle of pressure. It feels like you're in an ever-tightening vise grip, except worse. There's literally pressure coming from every direction -- up and down, forward and back, to the sides -- twisting you all at the same time through different parts of the body." -- Eric Fry, USA prop
"I was 18 in my first adult rugby scrum. I collapsed it, then got kneed in the face by the other prop. After the game, he came into the changing room with a can of beer for me!" -- Adam Jones, ex-Wales and British & Irish Lions prop
"It's a place of self-evaluation. It's a place of celebrating your mates when you dominate. It's a place to build character when you don't. It's a place where you reveal your inner self. It's a place where you earn the eye contact of your brother. It's a place where the slow ones go to get their glory, under the radar with no fuss made. For me, it is the best place of all." -- Adriaan Strauss, ex-South Africa captain and hooker
* The Rugby World Cup kicks off at 6:45 a.m. ET on Sept. 20 on NBC Sports Gold.