Will 48 Teams Mean More World Cup Upsets?

The expanded World Cup invites an obvious prediction: more teams, more matches, more weaker sides in the mix — surely more upsets. It is a reasonable intuition, and it might be right. But the structure of the new tournament also contains forces pushing the other way, and the honest answer is that the format does not unambiguously favour chaos. This is the competitive-balance case argued from both sides, because the interesting question is not "will there be upsets" — there always are — but whether 2026's design makes them more or less frequent than before.

First, what counts as an upset

An upset is a result that defies the pre-match expectation — the weaker side, by the ratings, beating the stronger. That framing matters because it ties "upset frequency" directly to two things: how often mismatched teams play each other, and how much randomness a single match carries. The expanded format changes both, and not always in the same direction. Keep in mind throughout that football is already a high-variance sport in which the better team loses a meaningful share of matches; we are asking whether 2026 nudges that baseline up or down, not whether upsets are possible.

The case for more upsets

Three arguments push toward more chaos. The first is simple volume: 104 matches instead of 64 is far more opportunities for a surprise, so even at a constant per-match upset rate the tournament will contain more upset events. That is almost trivially true and worth stating, even if it is really about counting rather than competitive balance.

The second is the wider field. A 48-team tournament admits the least-ranked sides ever to qualify, which means more genuinely mismatched fixtures, especially in the group stage. More mismatches is more chances for the underdog to catch the favourite on a bad day. The flip side — that many of these games will simply be won comfortably by the stronger team — is real, but the additional spread of quality does create more of the lopsided ties from which upsets are sampled.

The third, and most structural, is the knockout round that begins at 32. Single-game knockouts are the purest upset machine football has, because they remove the averaging that a two-legged tie or a league provides — one match, one result, maximum variance. By starting the bracket at 32 rather than 16, the expanded format adds a full extra round of these high-variance, win-or-go-home games, and does so at a stage where some of the qualifiers are weaker sides who scraped through. More single-elimination matches involving more vulnerable favourites is, on its face, a recipe for shocks.

The case against

The counter-arguments are less intuitive but real. The first is seeding. The tournament is not drawn at random; the strongest teams are seeded to be kept apart in the group stage and, by the structure of the bracket, are steered away from each other early. Seeding is explicitly designed to protect the favourites from premature collisions, which suppresses the highest-profile upsets — the giant-versus-giant shocks — and tends to feed the strongest sides a softer early path. A format can add games and still funnel the elite safely through the opening rounds.

The second is that more games can let class show. Variance is the underdog's friend over one match, but it averages out over several. A team that must navigate a group of three and then a longer knockout run has more total matches in which its true quality can reassert itself; a fluke result in one game is more likely to be corrected by the next. Over a longer tournament, the cream has more opportunities to rise, which works against the underdog who needs everything to go right at once.

The third is subtler: an extra round can help the strong as much as the weak. The new round of 32 does add a high-variance game — but it also hands elite teams an additional fixture against, often, a clearly weaker opponent, which is an extra expected win, not an extra coin flip, for the favourites. Whether the round-of-32 expansion is net pro-upset depends on which effect dominates, and that is genuinely unclear in advance.

Why this is hard to call

The deep reason the answer is uncertain is that upset frequency is the product of competing levers, and the format pulls several at once in opposite directions. More matches and a wider field raise the raw count of upset opportunities; seeding and additional games for the elite work to contain the damage to the favourites. How a forecaster nets these out depends on assumptions a model has to make — particularly how much match-level variance to assume and how large a seeding-and-path advantage to grant the top teams — which is exactly the kind of choice that makes two careful simulations disagree, as set out in how a World Cup simulation works and, for league forecasts, why league projection models disagree. There is no clean theoretical answer; there is a balance of forces and a set of modelling choices.

What to actually watch for

The honest position is agnostic with a structure. Expect the number of upsets to rise simply because there are far more matches — that much is near-certain and not very interesting. Whether the rate of upsets per match rises, and whether the marquee favourites are more likely to fall, is the open question, and it hinges on how the new round of 32 and the seeding interact. The thing to track is not the early group-stage mismatches, which will mostly go to form, but the round-of-32 ties between a seeded contender and a weaker qualifier: that fixture, repeated across the bracket, is where the format's pro-chaos and pro-class forces meet head-on. The related question of whether anyone outside the traditional powers can actually break through — a different cut of the same balance — is taken up in confederations at the World Cup. And the search for the specific teams positioned to spring those shocks is the subject of how to spot a dark horse.

Sources & further reading

• Free textbook: Chapter 20: Predictive Modeling — the theory behind this, at DataField.dev.
• FIFA — the official format, seeding principles and bracket structure for the expanded tournament.
• FBref — international results and ratings inputs for assessing pre-match expectation and therefore upsets.
• ClubElo — a rating system that frames what "the favourite" and "the underdog" mean in any given match.
• StatsBomb — event data and research on match variance and competitive balance.