LONDON — It was a rough opening night in the pool for defending Olympic champions, above all a certain Michael Phelps, but it was a historic night for the Chinese.

Sun Yang became the first Chinese man to win an Olympic swimming title by pulling away from Park Tae-hwan on the final two laps to secure the 400-meter freestyle in an Olympic record time. Then, 16-year-old Ye Shiwen smashed the world record in the women’s 400 individual medley by more than a second: all the more remarkable because she swam the last 50 meters in a faster time than the new men’s 400 I.M. champion, Ryan Lochte, swam his last 50 meters.

That is surely an Olympic first.

“I honestly didn’t realize how far ahead I was,” said Ye, a short-haired teenager from the Chinese city of Hangzhou, which, until now at least, was more famous for its lake.

What was also striking about Ye’s record swim of 4 minutes 28.43 seconds was that she managed it in a textile suit while the record she broke — Stephanie Rice’s 4:29.45 — was set in the age of polyester suits and serial record breaking.