Key takeaways
- Seeds are taken straight from the ranking list shortly before the event, roughly a week before at the Grand Slams and the WTA, and the most recent list at the ATP.
- In a 128-player draw with 32 seeds, the placement rules keep the top two apart until the final, the top four until the semi-finals, the top eight until the quarter-finals and all 32 until the third round.
- Seeds within each group are drawn at random into fixed lines, so a projected quarter-final opponent is a matter of the draw, not of ranking order.
- When a top-16 seed withdraws before the first day's order of play is released, the Grand Slam rules move the 5th or 17th seed into the vacated line and promote the next eligible player, while the WTA slots the next player eligible to be seeded straight in.
- Seeding controls who can meet whom and when; it does nothing to stop a seed losing to an unseeded player.
Seeding is how a tennis tournament protects its best-ranked entrants from each other. Before the draw, the event names its seeds, the highest-ranked players in the field according to the official rankings, and puts them on fixed lines of the draw sheet. Everyone else is then drawn at random into the lines that are left. In a 128-player draw with 32 seeds, the placement means the top two cannot meet before the final, the top four before the semi-finals, the top eight before the quarter-finals and any two seeds before the third round.
What seeding does not do is protect anyone from an upset. It controls who can meet whom, and when. The rules below are from the 2026 editions of the Official Grand Slam Rule Book, the ATP Official Rulebook and the WTA Official Rulebook.
Choosing the seeds
All three rulebooks require a seeded main draw, and none treats the seeding as official until the draw is actually made. The differences are in which ranking list counts and how many seeds a draw gets:
| Grand Slams | ATP | WTA | |
|---|---|---|---|
| Ranking used | The list dated about seven days before the tournament | The most recent ATP ranking list (a protected ranking does not count) | The WTA singles ranking as of the week before the tournament |
| Number of seeds | At least 16 in the singles main draw | 8 for 28- and 32-player draws, 16 for 48 and 56, 32 for 96 | 32 for 96 and 128, 16 for 48, 56 and 64, 8 for 28 to 32, 4 for 16, 2 for 8 |
| Wild cards | May be seeded | May be seeded | Eligible |
| Qualifiers | Not addressed in the seeding section | May be seeded if the main draw is made after qualifying ends | Not eligible, nor are lucky losers |
One Grand Slam detail is easy to miss. Entry and seeding use different lists. Direct acceptance into a Grand Slam singles draw is based on the ranking dated about 42 days before the event, but seeding uses the one from about a week before. A player who climbs in the last five weeks is still entered on the older number but seeded on the newer one. How tennis qualifiers work covers the entry side.
Placing the seeds on the draw sheet
The placement procedure is the same idea in all three rulebooks. Seed 1 goes on the first line. Seed 2 goes on the last: line 32 of a 32-line draw, line 64 of a 64, line 128 of a 128. The rest are drawn in groups, a pair for seeds 3 and 4, then fours and eights, into fixed sets of lines. For a 128-player draw with 32 seeds, the Grand Slam table gives these lines:
| Seeds | Drawn as | Lines available |
|---|---|---|
| 1 | Placed | 1 |
| 2 | Placed | 128 |
| 3–4 | A pair | 33, 96 |
| 5–8 | A group of four | 32, 64, 65, 97 |
| 9–12 | A group of four | 17, 49, 80, 112 |
| 13–16 | A group of four | 16, 48, 81, 113 |
| 17–24 | A group of eight | 9, 24, 41, 56, 73, 88, 105, 120 |
| 25–32 | A group of eight | 8, 25, 40, 57, 72, 89, 104, 121 |
The ATP's table for a 96-player draw uses the same 128 lines with 32 seeds, and every seed there receives a bye into the second round. The remaining players, qualifiers included, are then drawn into the empty lines from the top of the sheet downwards.
What the lines guarantee
Divide a 128-line draw into quarters (lines 1–32, 33–64, 65–96 and 97–128) and check where each group lands:
| Seeds | Each one sits in its own | So the earliest any two can meet is |
|---|---|---|
| 1 and 2 | Half | The final |
| 1 to 4 | Quarter | The semi-finals |
| 1 to 8 | Eighth (16 lines) | The quarter-finals |
| 1 to 16 | Sixteenth (8 lines) | The fourth round |
| 1 to 32 | Block of 4 lines | The third round |
That last row means seeds play only unseeded opponents in the first two rounds. The arithmetic is checkable against the line table above: no two of the 32 seed lines fall in the same block of four.
Why the groups are drawn, not ranked
Within each group, the order is decided by the draw, not by ranking. Seed 3 is equally likely to land in seed 1's half or seed 2's. Whichever of seeds 5 to 8 is drawn onto line 32 becomes seed 1's projected quarter-final opponent, and each of the four has the same chance. So "the 5th seed is in the top seed's quarter" is something the draw produces, not something the seeding list promises.
How much protection is that, compared with no seeding?
Picture the same 128 players drawn completely at random, with no seeds. Simple counting gives:
- The two best players land in opposite halves only 64 times in 127, about 50%.
- They meet in the first round about 1 time in 127.
- The top four end up in four different quarters about 9.8% of the time.
- The top eight end up in eight different eighths about 0.3% of the time.
Seeding turns each of those into a certainty. That is the whole of its job. The highest-ranked players are still free to lose to anyone they are drawn against, so a "projected" final between seeds 1 and 2 is a statement about the bracket, not a forecast of results.
When a seed withdraws
Withdrawals after the draw is made are where the three rulebooks differ most.
At the Grand Slams
If a seed withdraws before the order of play for the first day of the main draw is released, the 2026 rule book refills the line in a chain:
- A seed from 1 to 4 withdraws: the 5th seed moves into the open line. The 17th seed moves into the 5th seed's line, and the next highest-ranked player eligible to be seeded takes the 17th seed's line.
- A seed from 5 to 16 withdraws: the 17th seed moves into the open line, and the next eligible player takes the 17th seed's line.
- A seed from 17 to 32 withdraws: the next eligible player takes the line directly.
The newly seeded player leaves an unseeded line empty. That goes to the next player on the original entry list if qualifying has not begun, or to an eligible lucky loser if it has. Once the first day's order of play is out, a seed's vacancy is simply filled by an eligible lucky loser, with no reshuffle.
Take seed 3 withdrawing two days before the event. Seed 5 moves onto seed 3's line, seed 17 onto seed 5's old line, and the highest-ranked unseeded player becomes a seed on seed 17's old line. That player's former line is then refilled. The chain keeps the top lines in the hands of the strongest remaining seeds, and it changes only four lines of the draw.
There is also a bigger lever. If two or more of the top eight seeds withdraw more than 48 hours before the tournament starts, the tournament may choose to remake the draw or let it stand.
On the tours
The ATP has the same remake option, with a 24-hour threshold instead of 48. The WTA uses a more direct swap. If a seed without a bye withdraws after the draw but before the first match of that draw, the next player eligible to be seeded takes the vacated line. The next eligible entrant, whether a qualifier, lucky loser or alternate, takes the line that leaves open. Once play has begun, the open line simply goes to the next eligible entrant. Seeds who had a bye follow a separate set of steps.
Byes
In draws that are not a power of two, the top seeds receive byes into the second round. The ATP gives byes to the top four seeds in a 28-player draw, the top eight in a 56-player draw, and every seed in 48- and 96-player draws. The WTA's 2026 table sets 32 byes for a 96-player draw, 16 for 48, 8 for 56 and 24, 4 for 28 and 2 for 30, given to seeds in descending order.
Why seeding follows the ranking
Seeding is only as good as the ranking it is built on. That ranking is a rolling record of results, not a measure of current form. How tennis ranking points work explains how it is assembled, and ranking decay and scheduling shows why points dropping off can move a player in or out of the seeded group from one week to the next.
The same pressure runs through Tennis Career Simulator 2026, a fictional career game. You work from junior events through qualifiers and main draws toward championship events, against progressively stronger fields. Its ranking points expire over a rolling window, so planning which events to play is part of holding a position. Nothing in the game reflects a real player, tour or tournament.
New to the sport? Start with tennis scoring for beginners, then explore the tennis guides. The studio's other titles are under sports career and GM games.
Good to know
Frequently asked questions
How does seeding work in tennis?
How many seeds are there at a Grand Slam?
When can the top two seeds meet?
What happens if a seed withdraws before the tournament?
Can a wild card or a qualifier be seeded?
Sources
- 2026 Official Grand Slam Rule Book (opens in a new tab)Grand Slam Tennis — accessed
- The 2026 ATP Official Rulebook (opens in a new tab)ATP Tour — accessed
- 2026 WTA Official Rulebook (opens in a new tab)WTA — accessed
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