World Cup Semifinal Odds: Supercomputer vs Market

There are two rigorous ways to price a World Cup semifinal: run millions of match simulations through a structured model, or read the aggregated judgment of real-money prediction markets. The Opta supercomputer and the real-money markets on Polymarket and Kalshi frequently arrive at different numbers, and those gaps are where the analytical interest lies. When the model and the market disagree on world cup semifinal odds, one of them is mispricing something, and identifying which is the core exercise of this piece.

The 2026 FIFA World Cup semifinals consist of two matches. Match M101 kicks off on 14 July at 2:00 p.m. local time (UTC-5) at AT&T Stadium in Dallas, with the winner of France vs Morocco meeting the winner of Spain vs Belgium. Match M102 follows on 15 July at 3:00 p.m. local time (UTC-4) at Mercedes-Benz Stadium in Atlanta, where the winner of Norway vs England faces the winner of Argentina vs Switzerland. Both ties are single elimination: if level after 90 minutes, the match proceeds to two periods of 15 minutes extra time and, if necessary, a penalty shoot-out. The two winners advance to the final at MetLife Stadium.

Every Possible Semifinal Matchup, Priced

The table below covers all eight possible semifinal pairings, ranked by consensus probability. Each pairing probability is derived by multiplying each team's individual probability of reaching the semifinal stage, as published by Opta (live feed, 8 July) and Polymarket (7 July). The consensus column is the simple average of the two sources. Opta's figures come from its simulation model at The Analyst, while Polymarket prices reflect aggregated real-money positions tracked via the Neil Paine odds tracker.

The methodology is deliberately transparent. A team's probability of appearing in a given semifinal slot is taken directly from each source's published reach-semifinal figure. Multiplying the two relevant figures from the same source gives that source's pairing probability. Averaging across sources produces the consensus. This approach means the numbers are as independent as the two sources themselves, and any divergence between columns reflects genuine disagreement rather than rounding noise.

Where the Model Disagrees with the Market

The most significant gap sits with France. Opta assigns France a tournament-win probability of 27.3 percent, while Polymarket prices it at 33 percent and Kalshi at 34.1 percent, a spread of roughly six to seven percentage points. That divergence flows directly into the semifinal pairings involving France: Polymarket's higher France reach-semifinal figure of 78 percent against Opta's 73.9 percent inflates the consensus probability for France vs Spain and France vs Belgium relative to what the model alone would suggest. For a bettor, this implies the market is paying a premium to be on the France side of any pairing, and that premium is not supported by the simulation output.

In the opposite direction, the model is warmer than the market on both Switzerland and Norway. Opta prices Switzerland's tournament-win chance at 3.8 percent against Polymarket's 2.0-2.3 percent range, and Norway's reach-final probability at 17.1 percent against the market's 14 percent. Those gaps are smaller in absolute terms but proportionally meaningful: the model sees Switzerland as roughly 65-90 percent more likely to win the tournament than the market does. For the semifinal specifically, this manifests in the Norway vs Switzerland pairing, where Opta's 11.6 percent sits 2.6 points above Polymarket's 9.0 percent. On Spain, the two sources are close on tournament-win probability (Opta 21.3, Polymarket 19), but the market assigns a higher probability to Spain exiting in the semifinal against France, suggesting real-money traders are more pessimistic about Spain's ability to navigate that particular bracket half than the model implies.

World Cup Semifinal Predictions

France vs Spain (Consensus 54.7%)

This is the most probable semifinal pairing by a considerable margin, with a consensus probability of 54.7 percent. Opta prices it at 51.5 percent and Polymarket at 57.9 percent, the largest absolute gap of any pairing. France arrive with 14 goals scored across five matches, a perfect group stage, and Kylian Mbappe having become the all-time World Cup knockout-stage top scorer. Spain have yet to concede a goal in five matches, advancing past Portugal on a 90+1-minute substitute goal from Merino. The market's higher number for this pairing reflects its elevated France reach-semifinal estimate, which the model does not fully endorse. The Opta figure of 51.5 percent appears more defensible given Spain's defensive structure, which the simulation accounts for systematically rather than through sentiment.

England vs Argentina (Consensus 45.7%)

The second most likely pairing carries a consensus of 45.7 percent, with Opta at 43.1 and Polymarket at 48.4. Argentina hold a tournament-win probability of 17.3 percent per Opta and 19 percent per Polymarket, a moderate gap that the data attributes partly to Argentina's two consecutive narrow escapes: a 3-2 after extra time against Cabo Verde and a 3-2 comeback from 0-2 down against Egypt. The market appears to have moved more on those results than the model did. England, meanwhile, beat Mexico 3-2 at the Azteca with ten men, with Bellingham scoring twice and Kane adding a penalty. Quansah's suspension for the quarter-final is the one confirmed squad constraint in the data. Opta's more conservative 43.1 percent for this pairing implies the model is less convinced by Argentina's market momentum than real-money traders are.

Norway vs Argentina (Consensus 25.9%)

At 25.9 percent consensus, this is the most probable cross-bracket alternative in the Atlanta semifinal slot. The two sources are in near-agreement here: Opta 26.0, Polymarket 25.6. Norway eliminated Brazil 2-1 with Haaland scoring in the 79th and 90th minutes, and Haaland has scored in every World Cup match he has played in this tournament. Norway's reach-semifinal probability sits at 37.7 percent per Opta and 35 percent per Polymarket, making this the one pairing where the model and market are essentially aligned. Neither source offers a clear edge over the other, which suggests this probability is reasonably well-calibrated across methodologies.

France vs Belgium (Consensus 20.9%)

Opta prices this pairing at 22.4 percent, notably above Polymarket's 19.3 percent. Belgium's reach-semifinal figure is 30.3 percent per Opta and 25 percent per Polymarket, a gap that accounts for most of the difference. Belgium defeated the USA 4-1, with De Ketelaere contributing two goals and an assist. The model appears to rate Belgium's semifinal prospects more generously than the market, which may reflect the market's tendency to concentrate probability around France regardless of opponent. The Opta number at 22.4 percent implies a decimal price of approximately 4.5, suggesting the model sees this pairing as meaningfully more likely than market positioning implies.

England vs Switzerland (Consensus 18.2%)

Opta prices this at 19.3 percent, Polymarket at 17.0 percent. Switzerland reached the quarter-final via a 0-0 draw with Colombia followed by a 4-3 penalty shootout win, with Kobel saving and Vargas converting the decisive kick. Switzerland's reach-semifinal figure from Opta is 30.9 percent against Polymarket's 26 percent, which is one of the larger proportional gaps in the dataset and reflects the broader model-vs-market disagreement on Switzerland's tournament ceiling. England's path through the Azteca suggests resilience, but the model's warmer view on Switzerland implies this pairing is somewhat underpriced in real-money markets.

The Rest of the Field

Morocco vs Spain carries a consensus of 17.7 percent (Opta 18.2, Polymarket 17.1), with Morocco having beaten Canada 3-0 in the round of 16 and eliminated the Netherlands on penalties earlier in the tournament. The two sources are in close agreement here, suggesting this pairing is fairly priced across methodologies.

Norway vs Switzerland at 10.3 percent consensus (Opta 11.6, Polymarket 9.0) represents the pairing where the model-market gap is proportionally largest among lower-probability matchups, consistent with the broader disagreement on Switzerland. Morocco vs Belgium at 6.8 percent consensus (Opta 7.9, Polymarket 5.7) is the least likely pairing overall, with Opta again assigning meaningfully more probability than the market to the Belgium side of the bracket.

Semifinal Betting: Backing the Model or the Market

The value framework in a model-versus-market exercise is straightforward: when the model's implied probability exceeds the market's, the market price is theoretically too long and represents a potential edge. Converting probabilities to approximate decimal prices using the formula 1/probability makes the gaps actionable. Two pairings from the data illustrate this clearly.

First, Norway vs Switzerland. Opta prices this at 11.6 percent, implying an approximate decimal of 8.6. Polymarket prices it at 9.0 percent, implying approximately 11.1. The model sees this pairing as occurring roughly 29 percent more often than the market does. That gap is driven by the model's higher assessment of both Norway's and Switzerland's semifinal reach probabilities relative to market consensus. A bettor who trusts the Opta simulation over real-money positioning would regard the market price on this pairing as offering value. Second, France vs Belgium. Opta at 22.4 percent implies approximately 4.5, while Polymarket at 19.3 percent implies approximately 5.2. The model's warmer view on Belgium's bracket progress, relative to the market's tendency to discount non-France semifinal outcomes in that half, generates a gap of 3.1 percentage points that is consistent with the broader Switzerland and Norway disagreements identified above.

As with any form of wagering, stakes should be managed responsibly and within personal financial limits.

FAQ

How does the Opta supercomputer price the World Cup semifinals?
The Opta model runs large-scale match simulations using team and player performance data, producing probabilities for each possible tournament outcome. For the semifinals specifically, each team's probability of reaching the stage is published directly, and pairing probabilities are derived by multiplying the two relevant reach-semifinal figures. The live feed used here is dated 8 July, available at The Analyst.

What is the most likely 2026 World Cup semifinal pairing?
France vs Spain is the most probable semifinal pairing at a consensus probability of 54.7 percent, with Opta pricing it at 51.5 percent and Polymarket at 57.9 percent. It is the only pairing with a better-than-even consensus chance of occurring and reflects the strong tournament-win probabilities assigned to both nations by both sources.

Who wins the 2026 World Cup according to the model?
As of the Opta live feed on 8 July, France lead the tournament-win probability at 27.3 percent, followed by Spain at 21.3 percent and Argentina at 17.3 percent. Real-money markets on Kalshi assign France an even higher probability of 34.1 percent, with Argentina at 18.8 percent and Spain at 18.7 percent. The gap between Opta and the markets on France is the most notable disagreement in the current dataset.