LONDON, Aug. 4 (UPI) -- Saturday's highlights at the Olympics:
-- The amazing Olympic career of American Michael Phelps came to an end with the greatest swimmer of all time collecting his 18th gold medal. The next-best total is nine. Phelps' last race was the 400-meter medley relay, during which he swam the butterfly for 100 meters. It was the third leg of the relay and when he jumped in the pool the Americans were behind. When he was through, they were in front and headed to a victory.
-- Six gold medals for Britain on the busiest day at the Games thus far caused celebrations throughout the city. Three early wins in cycling and rowing were enough to get things going, and the three more in track and field during the evening were almost beyond belief. Britain won a national record 19 gold medals in Beijing and already has 14 in London.
-- Phelps was not the only one providing drama in the pool Saturday. The American squad of Missy Franklin, Rebecca Soni, Dana Vollmer and Allison Schmitt set a world record in winning the 400-meter medley relay, and China's Sun Yang shattered his own world mark in the 1,500-meter freestyle. Sun was fortunate not to be disqualified, however, after jumping in the pool before the starting tone sounded. Judges ruled he was distracted by noise in the arena and gave him another chance.
-- Serena Williams added an Olympic gold medal to her 13 major championships by completing a thorough dismantling of the field. In her six singles matches she allowed her opponents to win no more than three games in any set and finished things off with a 6-0, 6-1 blasting of Maria Sharapova.
-- The United States boxing team received the only bit of good news it has had lately when the sport's international governing body ruled American welterweight Errol Spence could keep fighting after all. Spence was defeated Friday, leaving the United States with no boxers remaining in the Olympic tournament. It was ruled Saturday, however, that the Indian fighter who defeated Spence should have had at least 4 penalty points assessed for continually holding onto the American during the bout.
-- The American men's basketball team found itself in jeopardy of a shocking setback against Lithuania with 5 minutes remaining. The U.S. team trailed by 2 points before ending the game on a 17-10 run fueled by LeBron James.
-- Guatemala won its first Olympic medal ever when Erick Barrondo finished second in the 20-kilometer walk. San Marino had a chance for its first medal as well in women's trap shooting, but Alessandra Perilli lost in a three-way shoot-off for second and third place.
-- In an unlikely turn of events, competitors from the United States and China won the same number of gold medals during the day (five) and also collected the same number of medals overall (11).
-- The 151st gold medal of the Olympics will be handed out Sunday, marking the midway point of the Games, and the United States leads China in golds -- 26 to 25.