NEW YORK – This is the third round of singles, when the seeded players at the U.S. Open are supposed to start meeting each other.
But early upsets have changed the dynamic, not that the contenders necessarily mind meeting upset upstarts rather than top-30 players.
MATCHES TO WATCH - MEN
This is one matchup that went off as scheduled, and it's the wackiest thing. Isner has a 4-2 record against the German, and those two defeats have come the last two years, in the third round of the U.S. Open.
What are the odds?
Not only is Estrella Burgos the only Dominican ever to have made the main draw at the U.S. Open, it's the first time for Estrella Burgos himself in a Grand Slam, at the advanced age of 34. Just to reach the third round is already a tremendous accomplishment for him; to give Raonic a tough match is a bonus. The acoustics on the Grandstand court will make the big Raonic serve sound even more supersonic than it already is in real life.
That this one is scheduled on Arthur Ashe Stadium is bit of head-scratcher, although the night session scheduling during Labor Day weekend tends to be a little thing because CBS takes over the broadcast window during the day, and gets its pick of the best marquee matches.
The charismatic, animated Kyrgios is the type of player you don't want to take your eyes off of for a second, because something's always happening. But keep the kids away from courtside, because the profanity level is pretty impressive. The veteran Robredo is a good foil for him.
MATCHES TO WATCH - WOMEN
 Serena WIlliams (USA) vs. Varvara Lepchenko (USA)
It's unlikely Williams will get much of a battle from her countrywoman, if Lepchenko's doubles match Friday is any indication. After the warmup, Lepchenko took a lengthy medical timeout to have more and more tape and wrap applied to her knee. You wonder why this didn't happen before she got out on court, as it's hardly a new situation. But it's doubtful that knee will be much better today.
 Victoria Azarenka (BLR) vs. Elena Vesnina (RUS)
Azarenka's screeches are already infamous, and they'll sound even louder inside the Grandstand. But Vesnina is no slouch; every time she hits the ball, she comes out with a "Hai-YAAAAAAAAAA!" cry that really doesn't seem to have a noticeable effect on the velocity of her groundstrokes.
 Petra Kvitova (CZE) vs. [Q] Aleksandra Krunic (SRB)
Krunic is always up against the giants; it's her lot in life because she's so diminutive. But she took care of a big, tall, strong-serving opponent in Madison Keys in the second round. Kvitova has two Wimbledon titles to her credit, and her leftiness adds another dimension. But Krunic has already done it once; you never know.