Last updated: July 6, 2026
Quick Definition
A knee to a grounded opponent is a knee strike thrown at a fighter who has any part of their body other than their hands or feet touching the canvas. Under the Unified Rules of MMA, kneeing a grounded opponent in the head is a foul.
What is a knee to a grounded opponent?
A knee strike is legal in MMA almost everywhere on the body, at almost any time. The exception is the head of a fighter who is “grounded,” meaning down on the canvas as defined by the ruleset in use that night. Knee that fighter in the head, and the referee will step in.
The rule exists for two reasons. The first is safety: a fighter who is down often cannot move their head or defend properly, and a knee arriving with full bodyweight behind it can cause severe head injuries. The second is competitive balance. If knees to the head were legal on the ground, a fighter trapped underneath an opponent in mount or side control would have almost no way to protect themselves, and grappling exchanges would become far more dangerous.
Knees to the body of a grounded opponent remain legal under the Unified Rules. The foul only covers the head. That distinction confuses many new fans, who assume any knee against a downed fighter is illegal.
What counts as grounded under the current rule?
The current definition took effect on November 1, 2024. The Association of Boxing Commissions and Combative Sports (ABC) approved it at its annual conference on July 23, 2024, and the amended rule reads: a fighter is considered grounded, and may not legally be kneed or kicked to the head, when any part of their body other than their hands or feet is in contact with the canvas.
In practice, that means hands no longer count. A fighter with one or both palms flat on the mat and their feet planted can still legally be kneed in the head. Referee Mike Beltran spelled this out in a California State Athletic Commission video: one hand down or both hands down, the strike is legal. A knee, a shin, a forearm, the backside, or the back touching the canvas makes the fighter grounded, and head knees and kicks become illegal.
| Opponent’s position | Knee to the head | Knee to the body |
| Standing | Legal | Legal |
| Feet planted, one or both hands on the mat | Legal (since Nov 1, 2024) | Legal |
| Knee, shin, forearm, backside, or back on the mat | Illegal | Legal |
The change closed a loophole fighters had exploited for years. Under the old wording, touching one palm to the mat instantly made a fighter grounded, so defenders would tap a hand down to make head strikes illegal, then lift it to attack. The new definition removed that game entirely, and it debuted in the UFC at UFC Fight Night in Edmonton on November 2, 2024.
One caveat: each athletic commission must adopt the new rules separately, and adoption has been uneven. At UFC 316 in June 2025, the New Jersey State Athletic Control Board still used the older definition, so a single hand on the mat made a fighter grounded that night. Fighters are briefed before each event on which version applies.
How the rule has changed over the years
The definition of a grounded fighter has been rewritten more times than almost any other rule in MMA. The original Unified Rules of 2001 borrowed from boxing: anything other than the soles of the feet touching the floor made a fighter downed. Fighters soon learned to touch a finger to the mat to buy protection.
The ABC voted 42 to 1 in 2016 to tighten the definition, requiring both hands (palm or fist down) or another body part on the mat. Many commissions never adopted it. A 2019 ESPN report noted an ABC survey had found at least 10 different MMA rulesets in use across North America.
A compromise took effect on January 1, 2020: one palm or fist flat on the floor made a fighter grounded, but fingertips did not. That version held until the 2024 amendment removed hands from the equation altogether.
What happens when a fighter lands an illegal knee?
The referee decides. If the foul is ruled intentional, the offender can lose a point or be disqualified outright. The best-known example came at UFC 259 in March 2021, when Petr Yan kneed a grounded Aljamain Sterling in the head and lost his bantamweight title by disqualification.
Accidental fouls work differently. If the hurt fighter cannot continue and the fight has not yet reached its halfway point, it becomes a no contest, an official result with no winner. Past halfway, the judges score whatever rounds were completed and announce what the rulebook calls a technical decision. Eddie Alvarez’s 2017 fight with Dustin Poirier ended as a no contest after Alvarez landed knees on Poirier while Poirier had a knee on the mat.
Referees can also pause the action, issue a warning, and give the fouled fighter time to recover. That is what happened when Arnold Allen kneed Movsar Evloev at UFC 297 in Toronto in January 2024, under Ontario’s stricter definition of a grounded fighter.
Knees to a grounded opponent vs. soccer kicks and stomps
Fans often lump these three fouls together. They are related but distinct. A soccer kick is a kick to the head of a downed fighter, swung like a footballer striking a ball. A stomp drives the heel or sole straight down into a grounded opponent. Both are illegal under the Unified Rules, along with knees to the head of a grounded fighter.
| Strike | Target | Unified Rules status |
| Knee to the head (grounded opponent) | Head | Illegal |
| Knee to the body (grounded opponent) | Body | Legal |
| Soccer kick | Head | Illegal |
| Stomp | Any grounded target | Illegal |
| Punches and elbows (grounded opponent) | Head or body | Legal |
Punches and elbows to the head of a grounded fighter stay legal, which is why ground and pound (striking a downed opponent from top position) is such a large part of the sport.
Rules by promotion
Not every promotion bans the strike. The Unified Rules govern the UFC, PFL, and most North American MMA, and they prohibit knees and kicks to the head of a grounded opponent. ONE Championship, based in Asia, permits knees to the head of a downed fighter under its Global Rules. The Japanese promotion PRIDE FC went further in the 2000s, allowing knees, soccer kicks, and stomps to a downed opponent’s head, which gave its fights a distinctly different character.
| Promotion | Knees to head of grounded opponent |
| UFC, PFL (Unified Rules) | Illegal |
| ONE Championship | Legal |
| PRIDE FC (defunct) | Legal |
Frequently Asked Questions
Can you knee a grounded opponent in the body?
Yes. Under the Unified Rules, knees and kicks to the body of a grounded fighter are legal. Only the head is off-limits.
Why did Petr Yan get disqualified at UFC 259?
Yan kneed Aljamain Sterling in the head while Sterling was grounded. The referee ruled it intentional, and Yan lost his bantamweight title by disqualification.
Are knees to a grounded opponent legal in ONE Championship?
Yes. ONE Championship’s Global Rules allow knees to the head of a downed opponent, unlike the Unified Rules used by the UFC.
Does putting a hand on the mat still make a fighter grounded?
No, not under the current Unified Rules. Since November 1, 2024, hands and feet do not count. Some commissions, including New Jersey as recently as UFC 316 in 2025, still use the older definition.
What is a no contest?
A result where the fight officially has no winner. It applies when an accidental foul, such as an illegal knee, stops a fight before the halfway point.
Sources
- CBS Sports. “Commission removes 12-6 elbows from Unified MMA rules, updates grounded opponent rule.” Accessed July 7, 2026.
https://www.cbssports.com/mma/news/commission-removes-12-6-elbows-from-unified-mma-rules-updates-grounded-opponent-rule/ - ESPN. “ABC seeks to clarify, unify grounded fighter rule.” Accessed July 7, 2026.
https://www.espn.com/mma/story/_/id/26643743/abc-seeks-clarify-unify-grounded-fighter-rule - Heavy Sports. “Explaining the New MMA Rules That Debuted at UFC Edmonton.” Accessed July 7, 2026.
https://heavy.com/sports/ufc/mma-elbow-knee-rule-changes-explained/ - Yahoo Sports / MMA Junkie. “New unified rules to make UFC debut in Edmonton.” Accessed July 7, 2026.
https://sports.yahoo.com/unified-rules-ufc-debut-edmonton-184016009.html - MixedMartialArts.com. “Big John McCarthy explains the unified grounded fighter rule.” Accessed July 7, 2026.
https://www.mixedmartialarts.com/editorial/big-john-mccarthy-explains-the-unified-grounded-fighter-rule:9a974193-251c-471e-aa0f-7191a28ec864/ - Sports Illustrated / MMA Knockout. “UFC 316 revives old rules that ban key techniques.” Accessed July 7, 2026.
https://www.si.com/fannation/mma/news/ufc-316-old-rules-banned-techniques - Bloody Elbow. “Another ‘downed fighter’ UFC rule change in the works.” Accessed July 7, 2026.
https://bloodyelbow.com/2024/01/30/ufc-mma-downed-fighter-rule-change/ - Wikipedia. “Downed opponent.” Accessed July 7, 2026.
https://en.wikipedia.org/wiki/Downed_opponent
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