Amanda Anisimova, Frances Tiafoe and career-defining matches for the Americans

MELBOURNE, Australia -- Before Wednesday, American teen Amanda Anisimova hadn't seen the second round at a Grand Slam. Heck, she'd never been to Australia before arriving in Melbourne last week. But after a dominant 6-0, 6-2 win over No. 24 Lesia Tsurenko in the second round, Anisimova, who has won all four of her sets, has folks wondering just how far into the draw she can go.

"When I got on court, I was focused," Anisimova, 17, said about Wednesday's match. "I was really relaxed and my game was really on today. I felt like a lot of competitiveness came out. I want to let my opponents know I'm here to stay and play a long match, so I'm going to fight for every single point."

Currently the youngest player ranked in the top 100 and the 2017 US Open junior champion, Anisimova had an encouraging 2018 season in which she made the fourth round at Indian Wells and the third round in Cincinnati. Born in Freehold, New Jersey, to Russian-born parents, Anisimova moved to south Florida with her parents and older sister, Maria, at age 3, and for most of her career has been coached by her father, Konstantin. At 5-foot-11, Anisimova is known for her aggressive game and powerful serve, as well as a calm focus well beyond her years.

At Indian Wells, the then-16-year-old used all of those tools to defeat two top-25 players, including then-No. 9 Petra Kvitova, who was in the midst of a 14-match win streak.

"That tournament definitely opened my eyes that I can play at a really top level," Anisimova said. "It was a confidence-booster, but it was also motivation, like I want to do this again. I want to get better and better. That was a great start to the year."

Unfortunately, a fractured bone in her right foot kept her out of competition for the next four months. She returned to tennis in July after spending a month training at the USTA National Campus in Orlando, and by the end of the season, was ranked in the top 100 for the first time in her career. (She's currently No. 87.)

"I trained a lot and prepared myself really well in the offseason, so I think I've got a lot of confidence right now," said Anisimova, who next plays 20-year-old Aryna Sabalenka in the third round. "It's great that I made it past two rounds here, but I want to keep going. This year, I want to make a huge breakthrough and I think I can do it. Hopefully I'll get to do some sight-seeing after the tournament, because so far, I've just been concentrated on playing. I just want to keep winning."

Anisimova wasn't the only up-and-coming American to win Wednesday. Here's a look at how the rest of the U.S. players fared:

Frances Tiafoe def. No. 5 Kevin Anderson 4-6, 6-4, 6-4, 7-5

Frances Tiafoe rolled up his right sleeve, flexed his biceps and proceeded to bang the muscle on his right arm several times.

"It was pretty cool," he said afterward. "I was talking with my boy Zach [Evendon, his coach] about it. Some celebration, like you do for the new year. In the offseason, I'm more worried about winning tennis matches. It is kind of an instinct thing. I hope the crowd liked it."

If the celebration was unusual, the performance was stunning. From a set and a break down, Tiafoe, 20, outplayed last year's Wimbledon runner-up, fifth seed Anderson, to win 4-6, 6-4, 6-4, 7-5. Tiafoe, who equaled his previous best Slam run by reaching the third round of the Australian Open, called it one of the biggest wins of his career.

"It means the world to me," a beaming Tiafoe said. "I lost to Kevin three times last year. Then a set and a break down, it looked as if he was going to get a fourth win. I just went to a different place. The fact that it was a Grand Slam, second seed I beat, obviously a top-five player, it's pretty big."

Tiafoe's father emigrated to the United States from Sierra Leone in 1993 and his mother followed him three years later, escaping the civil war. When Tiafoe was a year old, his father began working as a janitor at a tennis facility, and later, Tiafoe and his twin brother, Franklin, learned to play tennis.

It is just over six years since Tiafoe became the youngest player ever to win the the Orange Bowl, the most prestigious junior event in tennis. Since then, the American has made solid progress, climbing to a world ranking of 39 in 2018, a year that saw him beat several top players, including Juan Martin del Potro, his idol, on his way to his first ATP Tour title in Delray Beach.

That week was an indication of his talent; Wednesday's win was a hint that Tiafoe might just be ready to take the next step, a deep run at a Grand Slam event.

"I've been telling you guys, last year, I had a lot of wins," Tiafoe said. "Had a rough end to the season. Good offseason. Those are the matches I feel like I'm dangerous. I always play pretty good in those situations. I've been in those situations quite a lot. I'm starting to feel more comfortable finishing the match, not just playing a match."

Earlier this month, Tiafoe found himself playing alongside Serena Williams for the United States in the Hopman Cup, including a match against Switzerland, led by Roger Federer. With the pair on opposite sides of the net, 43 Grand Slam titles were on the court and it was an experience he enjoyed.

"I think that week definitely helped me long run," Tiafoe said. "We hit a lot, and I was struggling. She hits the ball so hard. The courts are fast. It was skidding. I mean, a little topspin maybe. I'm not used to the ball coming in that flat. That was something I really had to adjust to."

Tiafoe plays Andreas Seppi on Friday.

Taylor Fritz def. No. 30 Gael Monfils 6-3, 6-7 (8), 7-6 (6), 7-6 (5)

Broken only once in a 3-hour, 24-minute affair, Fritz won his first career Grand Slam match against a seeded player (1-7).

Fritz cracked 47 winners (16 fewer than Monfils) but played cleanly throughout the four-set battle.

"It being a Grand Slam, this is one of the best wins of my career," Fritz said. "So I'm happy to get through."

It won't get any easier for the 21-year-old American. On Friday, he faces Roger Federer. They played once, in Stuttgart, Germany, two years ago, and Fritz took a set off Federer before succumbing late in the third set. Fritz was only 2 years old when Federer played his first professional match.

"Really cool to step on the court with him again," Fritz said. "I'm excited for the opportunity. ... I grew up watching a lot of the guys I play today. Can't tell you how many times I watched Monfils highlight reels on YouTube."

Danielle Collins def. Sachia Vickery 6-3, 7-5

Collins is a little older than most of the "next generation" of American players, but she's still only 25. Collins continued her stellar play through two rounds. A round after upsetting No. 14 Julia Goerges, Collins served strongly, and her all-around aggressive play was too much for Vickery.

A two-time NCAA singles champ at the University of Virginia, Collins had never won a Grand Slam match before this tournament.

Collins next takes on 19th-seeded Caroline Garcia.