If a player gets injured in the Ryder Cup and cannot play in the Sunday singles matches, the "envelope rule" is activated. Each team captain submits their singles lineup along with a sealed envelope containing the name of one player designated to sit out if an opposing player cannot participate due to injury or illness. If such an injury occurs, the player named in the envelope also sits out, and the match between the two players is considered a half (draw), with both teams receiving half a point each. This rule ensures a fair outcome without forfeits when all 12 players from each team are meant to compete in the singles.
For injuries affecting players in earlier sessions (fourball or foursomes), the rule is less critical since there are always some players sitting out. The envelope rule is specifically designed for the Sunday singles when all players participate. If an injury happens shortly before or during the start of singles matches, there's a clause about withdrawals and potential re-pairings to maintain fair competition.
This rule has been rarely used historically, with crews only having to implement it a few times since its introduction in 1979. It notably came into discussion recently in 2025 due to Viktor Hovland's neck injury and potential inability to play in the Sunday singles.
