The swimmer finished second in the men's 200-meter butterfly on Tuesday. Phelps was edged at the wall by South Africa's Chad le Clos.
Le Clos finished with a time of 1 minute, 52.96 seconds. Phelps swam the distance in 1 minute, 53.01 seconds. Although it wasn't gold, the silver medal was Phelps' record-tying 18th Olympics medal.
Later in the day, Phelps — as part of the men's 4×200 relay team — won gold, his 15th gold medal and 19th medal overall, passing Russian gymnast Larissa Latynina as the athlete to receive the most medals throughout a career at the Olympic Games.
It's a historic day for Phelps and all Olympians, and a mark that's not likely to soon be matched.
Photo via Facebook/MichaelPhelps