By Gerard Gallagher, Olympics Writer
London, England (Sports Network) - Michael Phelps' latest Olympic medal was the same color as so many of the others.
Only this was the last one.
The winningest Olympian of all time headed into retirement after one final medal ceremony atop the podium.
Phelps won his 18th Olympic gold medal, and 22nd overall Saturday night after swimming the butterfly leg of the heavily-favored United States' 400-meter medley relay team.
Phelps -- swimming in his fourth, and he swears last, Summer Games -- finishes as the all-time leader in medals and gold medals at the Olympics.
He won the race with Matthew Grevers, Brendan Hansen and Nathan Adrian, then fought back tears in the middle stretch of the "The Star-Spangled Banner."
He was all smiles near the end of the anthem, and the U.S. teammates held up a white banner with the words: "THANK YOU LONDON." Someone near the top of the packed Aquatics Centre screamed "We love you, Michael!" and another tried unsuccessfully to start a "Michael! Michael! Michael" chant.
Later, Phelps was brought back out in front of the fans -- many hanging around for one final glimpse -- in a special ceremony honoring his achievements.
FINA awarded him a silver trophy on a white base and he stood on top of the medal podium once more. Then, he lingered for a while, walking around the pool, holding the trophy up for spectators and photographers. He joked with a volunteer who walked beside him.
It was some farewell.
Phelps won six medals in seven races here -- his only loss came Day 1 -- including another four golds and his first two silvers.
Grevers, the 100 backstroke champ, gave the Americans a lead after 100 meters but they trailed Japan after Hansen's breaststroke leg. But Phelps had them back on top by .26 seconds after 300 meters and 100 freestyle champion Adrian locked it down with a fast split, touching the U.S. team in 3 minutes, 29.35 seconds -- 1.91 ticks ahead of Japan.
The U.S. swept the medley relays on the last night of swimming.
Earlier, Missy Franklin became the first American female to swim in seven Olympic events when she led off in a record-setting win by the U.S. in the women's 400 medley team.
Franklin, Rebecca Soni, Dana Vollmer and Allison Schmitt swam the race in 3:52.05 to take .14 seconds off China's old world record from 2009. Australia ended 1.97 seconds back in second place and Japan was third.
Franklin, 17, swam the leadoff backstroke laps and won her fifth medal in London, including four golds to cement her place as the new young star in U.S. swimming.
MORE TO FOLLOW.
08/04 16:37:12 ET