Player A and B are playing in a small club tournament.
Rules format is medal play.
On a certain hole, both players are hitting their second shots, near each other, in the rough. Player A hits what he thinks is his ball on the green while player B hits what he thinks is his ball into a greenside bunker. Player B takes two to get out of the bunker, and finally gets on the green. Appropriately, player B is now on his fifth shot on the green while player A is playing his third on the green. After player B gets on the green, player A approaches his ball to mark and player B does the same.