>> reporter: american nina o'brien tumbled in this scary wipeout and was taken away on the stretcher. worry written on the faces of her competitors. tonight the u.s. ski team says she is awake and alert. o'brien's olympics may be over, but for shiffrin, this is just the start. >> i want to hide the disappointments, but i'm also not going to dwell on that. that's not going to help me at all. >> quad number one. >> reporter: in figure skating, 15-year-old kamila valieva became the first woman to land a quad at the olympics. she did not one, but two, while the u.s. took silver in the team competition. but the good news was dampened by word that u.s. figure skate ervin sent zhao tested positive. >> the pain of it all is pretty insane. on instagram, zhou reflected on what it took to get him here. >> but you had a dream. you followed it. you made sacrifices and dedicated your life to it. >> big, big game. >> reporter: while the wait for test results was responsible for a delay in the