Alexis Blokhina had faced Russia's Diana Shnaider three times in ITF J1 tournaments this year on clay and grass, losing on all three occasions.

In their fourth meeting on Court 17 at the USTA Billie Jean King Tennis Center in Flushing Meadows on Tuesday, the 17-year-old from Florida got her revenge, taking out the No. 3 seed 6-2 7-6(5) in the second round of the US Open Junior Championships.

Rather than complaining about yet another meeting with Shnaider, Blokhina looked at the positives from her performance in those losses.

"I told myself, the last time you played her, you were right there," Blokhina said. "The other times it wasn't like she was taking me off the court, or that I couldn't stay with her. But in the tight moments, she would play more mature than me and that's what got her those close three-set matches. Today, I just told myself to relax and just go for it."

Blokhina counted the US crowd, including her many friends and family in attendance, as an advantage, just as her first match on Monday, where she defeated another left-hander. But when she went up 6-2, 4-0, Blokhina let her focus waver, losing four straight games.

"I thought, oh my gosh, I could actually finish this for once," Blokhina said. "I got too ahead of myself, not even thinking about how to play tennis. I was hoping for her to miss, rather than my playing. So when it got to 4-all, I was like, you've lost so many times playing this way, you can't do this again. So I just started to go for everything again."

Blokhina had three match points with Shnaider serving at 5-6, but credited the Russian with stepping up her game to deny her. But at 5-all in the tiebreaker, Blokhina committed to her own advice to play aggressively, blasting a huge forehand winner to earn a fourth match point. This time, she converted, when Shnaider sent a forehand into the net.

"At 5-5 I said, you're not losing this again, you're not losing this opportunity, you step up and take it," Blokhina said. "I didn't realise on match point that she missed in the net. When she stopped, I just got goosebumps all over my body. I ran to my dad and my mom, I had tears in my eyes, I couldn't believe I did it."

Blokhina, who is one of four American girls in the round of 16, will face unseeded Petra Marcinko of Croatia, who beat No. 16 seed Ashlyn Krueger  3-6 6-4 6-3 on Tuesday.

The reigning Wimbledon champions had mixed results on Tuesday as they played their first junior slam matches since their triumphs on the All England Lawn Tennis Club's famous Court One in July.

Samir Banerjee, the No. 2 seed this week, made quick work of Max Rehberg of Germany, delighting the fans in the Grandstand with a 6-0 6-4 victory.

But Ane Mintegi Del Olmo of Spain was not as fortunate. Playing on Court 14, in front of no more than a dozen fans, the No. 4 seed fell to Solana Sierra of Argentina 4-6 7-5 6-3.

The No. 4 seed in the boys' draw, Bruno Kuzuhara, also exited in his first match of the tournament, with qualifier Jakub Mensik of the Czech Republic posting a 6-3 4-6 6-3 win.

Top boys' seed Juncheng Shang had a 67-minute first set with American wild card Aidan Mayo, but the 16-year-old from China came through with a 7-6(5) 6-3 victory. 

Girls' top seed Victoria Jimenez Kasintseva had a much easier time in her first match of the tournament, defeating qualifier Theadora Rabman of New York 6-1, 6-0.

This is the third consecutive junior slam that Jimenez Kasintseva has been the No. 1 seed, but the 2020 Australian Open girls champion doesn't dwell on that.

"Even though I'm number one, I am trying not to think about it," said the 16-year-old from Andorra, who recently reached the final of a $60,000 ITF World Tennis Tour event in Spain. "It's just the result of the matches and tournaments I've won. I'm kind of used to it now. It's doesn't matter if I'm No. 1, No. 2 or not seeded."

Jimenez Kasintseva knew that she had to project her own confidence, recognising that Rabman had nothing to lose in a match against the world No. 1. So she took to heart the advice she received from the coach of Arantxa Rus, who beat her in the final in that WTT tournament Spain last month.

"He told me I have to make the opponents believe that they can't beat me," Jimenez Kasintseva said. "So today, I tried to use that. I had to get in her head and make her believe she cannot beat me. I try to play aggressively, make her understand she cannot make winners. I tried to hit hard and even though I make mistakes, I didn't care, I didn't want her to think she could make a winner."

Jimenez Kasintseva will next face two-time Orange Bowl finalist Jana Kolodynksa of Belarus, who advanced when No. 14 seed Dana Guzman of Peru retired after losing the first set 6-2.