Former Alabama All-American Amari Cooper will wear No. 18 in his first game with the Buffalo Bills on Sunday afternoon. On Sunday night, wide receiver Davante Adams will make his New York Jets debut in No. 17.

Both Pro Bowl pass catchers were traded last week, with Cooper joining the Bills from the Cleveland Browns and Adams joining the Jets from the Las Vegas Raiders. But Adams got to keep the number he has worn throughout his NFL career, while Cooper will be in his fourth NFL number.

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Asked about his new number during his introductory press conference, Cooper indicated it had no special significance but said he had a choice of only two digits, which was true if the wide receiver wanted to keep a number in the single digits or teens. When Buffalo acquired Cooper, the only numbers from 0 to 19 not in use were 16 and 18.

Cooper wore No. 2 with the Browns. Kicker Tyler Bass wears number 2 for the Bills. Players regularly give up jersey numbers to new teammates who are more established in the NFL, sometimes in exchange for financial gratitude.

But Cooper couldn’t even have purchased the number from Bass because NFL rules prohibit players from changing numbers during a season without switching teams.

“For competitive reasons, no player may change his uniform number once the regular season begins,” the rule reads. “Practice squad players who are not on the active roster for a regular season game may change jersey number to make an approved number available to a new player on the active roster. Special exceptions to this rule may be considered by the NFL Football Operations department depending on the circumstances (for example, if a player is traded to another team).

No exception was made for Cooper, just as there wasn’t one when he was traded from the Raiders to the Dallas Cowboys during the 2018 season. In that case, he switched from No. 89 to No. 19 because Blake Jarwin was already in the 89 for the Cowboys.

The Bills have players in the 19 and 89 — wide receivers KJ Hamler and Jalen Virgil, respectively — but they’re on the practice squad, so those grades were available under the rule if Cooper tried to work out a change.

The No. 9 that Cooper wore at Alabama will be worn in Buffalo by safety Taylor Rapp.

The NFL made an exception to the number rule for Adams.

When New York acquired Adams, rookie wide receiver Malachi Corley was in the No. 17 jersey. But Corley will wear No. 14 on Sunday night, while Adams will be in the No. 17 jersey on Sunday night against the Pittsburgh Steelers.