Seed ( sports ) A seed is a preliminary ranking that can be used in arranging a sports tournament . It is called a seed because of the analogy with plants where the seed might grow into a top rank at the end of that tournament , or might instead wither away . Players / teams are ' planted ' into the bracket in a manner that is typically intended so that the best don ' t meet until later in the competition . One version of seeding is where brackets are set up so that the quarterfinal pairings ( barring any upsets ) would be the 1 seed vs . the 8 seed , 2 vs . 7 , 3 vs . 6 and 4 vs . 5 ; however , this is not the procedure that is followed in most tennis tournaments , where the 1 and 2 seeds are placed in separate brackets , but then the 3 and 4 seeds are assigned to their brackets randomly , and so too are seeds 5 through 8 , and so on . This may result in some brackets consisting of stronger players than other brackets , and since only the top 32 players are seeded at all in Tennis Grand Slam tournaments , it is conceivable that the 33rd - best player in a 128 - player field could end up playing the top seed in the first round . Rankings of tennis players are generated by computers , and players tend to change ranking positions gradually , so that a more equitable method of determining the pairings might result in many of the same head - to - head matchups being repeated over and over again in successive tournaments . Sometimes the remaining competitors in a single - elimination tournament will be " re - seeded " so that the highest surviving seed is made to play the lowest surviving seed in the next round , the second - highest plays the second - lowest , etc . This may be done after each round , or only at selected intervals . In American team sports , for example , both the NFL and NHL employ this tactic , but the NBA does not ( and neither does the NCAA ) . MLB does not have enough teams in its playoff tournament where re - seeding would make a difference in the matchups . ( The NFL is at the minimum , which is 6 from each league [ or conference in the NFL , NBA or NHL ] for a total of 12 . ) The NBA ' s format calls for the winner of the first - round series between the first and eighth seeds ( within each of the two conferences the league has ) to face the winner of the first - round series between the fourth and fifth seeds in the next round , even if one or more of the top three seeds had been upset in their first - round series ; critics have claimed that this gives a team fighting for the fifth and sixth seeding positions near the end of the regular season an incentive to tank ( deliberately lose ) games , so as to finish sixth and thus avoid a possible matchup with the top seed until one round later . In some situations , a seeding restriction will be implemented ; from 1975 until 1989 , the National Football League and , since seeding began in 1998 , MLB have a rule where at the conference or league semifinal , should the top seed and last seed ( wild card ) be from the same division , they may not play each other ; in that case , the top seed plays the worst division champion ; the second - best division champion plays the wild card team .