investigated. we know it was under a car and that s about it. we ll continue to follow this for more information on that. a wild day in london from extreme disappoint to a golden moment for an american teenager, we start though with a 16-year-old chinese swimmer who did one lap faster than ryan lochte. it s raising doping suspicions. atika schubert is live in london. reporter: it was an incredible performance, she basically won at the 400 meter individual medley with stunning speed. she was literally for the last 50 meters faster than the u.s. gold winner in the same event, ryan lochte for the mens. as you can imagine, a lot of speculation into possible doping. here s what the international olympic committee had to say about it. so the sudden rise in the performance or a surprise win be primarily suspected for being acheat, sport is a danger for sure because it partially ruins the charm of competitive sport if a surprise win is surrounded by suspicions and question marks.