Valve has published detailed rules for the Swiss system during the group stage of The International 2025. The changes pertain to the order of side and pick selection, team ranking criteria, and the specifics of paired matches at various stages of the tournament.

Order of Side and Pick Selection
In Best of 3 matches, priority is determined by a coin toss:
1st map — the coin toss winner chooses the side or pick.
2nd map — the coin toss loser chooses the side or pick.
3rd map — a new coin toss is conducted, and the winner chooses.

In Best of 5 matches, the order is different:
1st map — the upper bracket winner makes the choice.
2nd map — the lower bracket winner makes the choice.
3rd map — again, the upper bracket winner chooses.
4th map (if applicable) — the lower bracket winner chooses.
5th map (if applicable) — a new coin toss is conducted.

Swiss Pairing System
The Swiss system with several modifications is used to determine pairings in the group stage:

Teams with the same results play against each other.
Repeat matchups are avoided as much as possible.
Priority is given to the smallest difference in opponent ratings.

Team Ranking Criteria:

Number of matches won.
Number of matches lost.
Win percentage by maps.
Total number of victories by opponents the team has played against.
Average win percentage of opponents.
Coin toss (in case of a tie).

Round Features
Round 1 — teams are divided into two groups, and pairs are assigned by the organizer.
Rounds 2–3 — matches are held only within their group.
Round 4 — teams face only representatives from the other group.
Round 5 — the standard Swiss system applies without restrictions.

In the elimination round, teams with a 3-2 result play against those with 2-3. Here, the difference in opponent ratings is maximized.

Final Seeding
The top eight teams that pass the group stage will secure spots in the playoffs. Their positions will be determined by the final Swiss system ranking.