US Open 2021: Teenagers Carlos Alcaraz and Leylah Fernandez continue to make history

It's been a stunning few days at the US Open. The women's No. 1 and No. 3 seeds are out, and so is the men's No. 3 seed. Young phenoms have notched statement wins. Little known players have made names for themselves with unexpected upsets.

In short, anything can happen at the US Open, and during Round 3, anything did.

The Round of 16 on Sunday, and there's even more at stake: a trip to the US Open quarterfinals. Every match matters, and there's upset potential everywhere you look.

Carlos Alcaraz continues run

The US Open quarterfinals will feature a teenager.

Spanish 18-year-old Carlos Alcaraz followed up an upset of No. 3 seed Stefanos Tsitsipas by defeating Peter Gojowczyk 5-7, 6-1, 5-7, 6-2, 6-0 in the fourth round of the tournament.

Per ESPN, Alcaraz is the youngest man to reach the quarterfinals of the US Open since Michael Chang back in 1990.

Alcaraz will face another young player, though not quite as young, in Canadian Felix Auger Aliassime, who defeated American Frances Tiafoe 4-6, 6-2, 7-6 (8-6), 6-4 on Sunday.

Aryna Sabalenka looks like the favorite now

In a US Open with Naomi Osaka and Ashleigh Barty eliminated, No. 2 seed Aryna Sabalenka is the new betting favorite to take her third Grand Slam title. She certainly looked the part on Sunday.

The 2019 US Open and 2021 Australian Open doubles champion defeated her doubles partner Elise Mertens 6-4, 6-1 to advance to the quarterfinals.

Here is how dominant Sabalenka was when she actually got her serve in bounds: 22 percent of Mertens' 41 points won were Sabalenka double faults. Sabalenka won 74 percent of her first serve points and 82 percent of her second serve points, plus four out of five break points.

Awaiting Sabalenka in her second straight Grand Slam quarterfinal will be either No. 8 seed Barbora Krejcikova or No. 9 seed Garbiñe Muguruza. Whomever it is, Sabalenka remains BetMGM's favorite to win the tournament at +250 odds.

The Leylah Fernandez Show claims another champ

Two days after defeating two-time US Open champ Naomi Osaka, unseeded teenager Leylah Fernandez took down another former champ.

This time it was No. 16 seed Angelique Kerber, who won the tournament in 2016. Fernandez topped the German in a 4-6, 7-6 (7-5), 6-2 thriller. The Louis Armstrong Stadium crowd say Fernandez fall behind a set and a break early, but roar back to force a tiebreaker:

Fernandez dominated from there, and sealed her first ever trip to a Grand Slam quarterfinal.

Botic van de Zandschulp upsets Diego Schwartzman

The upsets just keep on rolling at Flushing Meadows. Just four days after beating the No. 8 seeded player, Botic van de Zandschulp took down No. 11 Diego Schwartzman in a roller coaster five-set thriller. Van de Zandschulp won 6-3, 6-4, 5-7, 5-7, 6-1, becoming the first men's singles qualifier to reach the US Open quarterfinals since 2008.

Early on, it looked like it was completely over for Schwartzman. Van de Zandschulp won the first two sets by decent margins, keeping Schwartzman off balance with his clean and precise play. But it was far from over. Schwartzman clawed his way back in the third set, staying with van de Zandschulp and playing aggressive, fearless tennis even as van de Zandschulp was just one game from winning the match. He took advantage of van de Zandschulp getting overexcited to tie the set 5-5, then went on to win his first set 7-5.

It looked like Schwartzman was turning the corner after taking the third set, but he still couldn’t manage to get away from van de Zandschulp. Down 5-4, he survived two van de Zandschulp match points to tie the set and give himself one more chance for survival.

The fifth set would decide it all. Van de Zandschulp won the first game, which was a good sign for him since he was starting to look seriously exhausted. Then he won the second and third as Schwartzman started getting a little wild. He found himself up 5-1, staring at match point No. 3, when he again started to tighten up. He let Schwartzman back into the game until they were tied 40-40 and trading advantages. Finally at match point No. 4, van de Zandschulp finally put Schwartzman away to seal the win.

Van de Zandschulp, who has climbed from 117 to 61 in the worldwide rankings since the beginning of the tournament, will face the No. 2 seed Daniil Medvedev in his first-ever Grand Slam quarterfinal.

Daniil Medvedev easily defeats Daniel Evans

It was a ho-hum match for Daniil Medvedev, who beat Daniel Evans in straight sets to advance to the quarterfinals. He bested Evans 6-3, 6-4, 6-3 in just 1 hour and 43 minutes.

This felt almost like a maintenance match for Medvedev. He never looked like he felt seriously threatened. That's not to say that Evans didn't put up a fight, of course.

But Evans' best efforts couldn't rattle Medvedev, who was clinical and exact.

Medvedev will face Botic van de Zandschulp in the quarterfinals.

Elina Svitolina powers past Simona Halep

Upset fever may be on the rise at the US Open, but Elina Svitolina hasn't caught it. The No. 5 seed got past two-time Grand Slam champion Simona Halep, the No. 12 seed, with a 6-3, 6-3 win.

Svitolina had hiccups in both sets, letting Halep get a foothold that could possibly hoist her to an upset, but she played solid, calm tennis throughout. But both players brought their A-game to the court. There were numerous long rallies, some won by Halep, some by Svitolina, but they both made some incredible shots to try and save the point.

Halep just couldn't catch Svitolina when she got ahead, and she wasn't helped by the 22 unforced errors she made, almost double the number Svitolina had.

Svitolina is now one step closer to making it to the final of a Grand Slam tournament, something she's never done before. She's gotten as far as the semifinals at both Wimbledon and the US Open, but has never managed to get farther. Now she's two matches away from the US Open final.