NEW YORK -- When American swimming sensation Katie Ledecky added to her climbing total of career visits to NBCs Today show Monday -- this time to talk about how life has changed since she set two world records and won five medals at the Rio Summer Olympics, four of them gold -- she smiled and squirmed in her seat as the five hosts on the set took turns good-naturedly kidding her about her record-shattering start to her freshman year at Stanford University this fall.It already has included a 65-second rout in a 1,650-yard college invitational race Sunday in which Ledecky ... um ... beat the runner-up by four laps.Sooo, that basically means you get out of the pool, have coffee and a donut, and wait for everyone else to finish? TV host Savannah Guthrie needled.When the 19-year-old Ledecky was too polite or sheepish to parry back, the segment only got funnier.Wait -- she broke another record in just the last 20 seconds! Guthrie added.And on the way to the event tonight, shes going to break another record! Matt Lauer boomed, causing Ledecky to shake her head and blush again.Ledecky was in New York with 40 of her Olympic medal-winning teammates for USA Swimmings annual Golden Goggles Awards on Monday night, a black-tie year-end benefit that recognizes the U.S. teams best performances each year. Michael Phelps, Missy Franklin, Libby King and Maya DiRado were among the others who attended. Ryan Lochte did not.Ledecky has replaced Phelps as the most riveting figure in U.S. swimming. But as scintillating as her first three months at Stanford have been -- starting with the fact she set an NCAA or American record in every race she swam through Nov. 15 -- there was another woman sharing the red carpet with her at the Marriott Marquis hotel who was also impossible to ignore.That was Stanford teammate Simone Manuel, the first female African-American swimmer to win an individual event at an Olympic Games and, as of last weekend, the first person anywhere to beat the amazing Ledecky in her last 74 finals in a race above 100 meters.Manuel, a junior, defeated Ledecky on Saturday in the 200-yard freestyle during an invitational at Ohio State, clipping Ledecky by .26 of a second.No, I didnt know the [length of the streak], a surprised Ledecky said, grinning as if even she found it cool.I didnt know it, either, but its not like Im out of the park yet, Manuel joked, speaking a little further down the red carpet from where Ledecky was taking questions. I still have to race her every day in practice, at nationals, at NCAAs.Manuel was right. Its just a start. But dont overlook the significance of their head-to-head battles; their races should be fascinating -- maybe even transformative -- for both swimmers.With 10 Olympic medals already won between them, the 20-year-old Manuel and Ledecky could anchor the U.S. swim team for a few Olympics to come.I know I definitely want more, Manuel said.The idea of Ledecky, especially, finally having anything close to a true rival -- another female swimmer who can push her and beat her while training on the same team and sometimes in the same lane day in and day out, sets up an interesting dynamic for both women as they slowly start looking ahead to the 2020 Tokyo Games.I dont look at it like shes a frenemy, Ledecky laughed, pointing out she and Manuel were roommates in Rio, and have been roommates for four years at international meets, so were good buddies.We both love to race and we both love to compete. We race all the time in practice and Simone beats me at least a couple times a week [in sprints]. So its a great environment every day. And I dont consider it a loss when its my teammate thats beating me, anyway. Were both racing our hardest for Stanford and excited about what could follow.Ledeckys coaches are always looking for fresh challenges to throw her way. Shes been so peerless at the distance events for so long, there is talk now about dropping her down to the 100-meter free (Manuels gold-medal individual event in Rio), and maybe adding the 400 individual medley to the 200, 400, 800 and 1,600 events and world records she currently owns.Many argue Ledecky -- not LeBron James, Usain Bolt, Lionel Messi or anyone else you can name -- is the most dominant athlete in the world today. Its only news now when she doesnt win.Manuel shoulders a different set of challenges. Though she also won the gold in the 4x100 medley relay and silver in the 50 free and 4x100 freestyle relay in Rio, she said in the past that trying to become the first African-American to win any Olympic swimming medal was difficult for her at times, as if so much history weighed on every stroke. She was expansive on the topic in Rio, paying homage to groundbreakers that came before her and embracing a chance to weigh in on matters like police violence against African-Americans back in the United States.But Monday, she pulled back on the non-swimming topics a little.When an Afr