On day six of competition, in the prelims of the 100-meter butterfly, Shields tied for 12th overall with a time of 51.57 and advanced to the semifinals. Later in the evening, Shields became one of the first individuals to swim in the first male and female, mixed gender, swimming race in the history of the Olympic Games by swimming the butterfly leg of the 4x100-meter mixed medley relay in the prelims. The relay ranked second for both prelims heats and advanced to the final.