Biggest Rating Upsets in UFC History

The most shocking results, where the lower-rated fighter beat a far higher-rated opponent

In mixed martial arts, the favorite doesn't always win — and MMA.SOCIAL's own ELO rating lets us measure how shocking each result was on paper. Every fighter carries a rating into a bout; when a heavy underdog beats a far higher-rated opponent, the gap between their two ratings at that moment is the size of the upset. The leaderboard below ranks the biggest shocks in UFC history using each fighter's real ELO on fight night — not their current or peak rating, so the numbers reflect how the fight actually looked on paper at the time. The largest rating gap on record is Chris Weidman's win over Anderson Silva at UFC 162: Silva vs Weidman — a +546-point ELO swing (1,120 vs 1,666).

How We Measure UFC Upsets

Upsets are ranked by the difference between each fighter's ELO rating at the time of the fight — the rating they carried into the bout, not their current or peak rating. Because we store every fighter's pre-fight ELO, the gap you see is exactly how lopsided the matchup looked on paper that night. The winner was the underdog: their pre-fight ELO was lower than their favored opponent's, and the larger the gap, the more shocking the result.

What counts as a true upset?

Not every underdog win is a genuine upset. A fighter rated 20 or 30 points below their opponent winning is well within the noise of the sport. The results on this page are the outliers — bouts where a fighter beat someone rated hundreds of ELO points higher, often a reigning or former champion at the peak of their reign. Those are the nights that rewrite divisions and end dynasties, and ELO captures them cleanly because it already accounts for who each fighter had beaten coming in.

What this number does not tell you

ELO is a model, and it is worth being clear about what it can and cannot see. It knows results, opponents and dates; it does not know that a favourite fought hurt, missed weight badly, took the bout on six days' notice, or was three years past their peak. It is also not a betting line — nothing on this page comes from a sportsbook, so a fight can look enormous by rating and only mildly surprising to the market, or the reverse. And the rating a fighter carries in depends on how much of their career we hold: a newcomer with two Octagon bouts is rated on thin evidence, which can make an early win look more or less dramatic than it felt at the time. Read the gap as a measure of how the records lined up, not as a verdict on how the fight should have gone.

Why upsets matter in MMA

MMA is the most volatile of the major combat sports: four-ounce gloves, five-minute rounds, and a dozen ways to lose mean any fighter is one mistake from defeat. That volatility is exactly why upsets are the heartbeat of the sport — they reset rankings, mint new contenders, and remind everyone why the fights are still contested inside the cage rather than decided on paper. Browse MMA.SOCIAL's ELO ratings to see where these giant-killers and the fighters they beat stand today, see the fighters with the most wins over UFC champions and the fastest rising ELO fighters, or explore more UFC statistics.