This is a big day for Michael Phelps. The swimmer took home the gold medal in the 4x200 freestyle relay—earning him his 19th Olympic medal, the most ever. It's also his 15th gold medal. Earlier on Tuesday, Phelps won silver in the finals of the 200m butterfly. He went into the fly final with the fourth-fastest qualifying time of 1:54.53, but was only 0.28 seconds behind Japan’s Takeshi Matsuda. He only had about an hour to rest before the men's 4x200 relay, where he edged past Serbia's Milorad Cavic by 0.01 seconds.