Kwiatkowski will meet Stanford junior Tom Fawcett after Fawcett came back from a set down to defeat Northwestern senior Konrad Zieba 3-6, 6-3, 6-0. Fawcett won 32 of 51 points in the third set while winning 62% of the points on Zieba's serve.
Ryan Shane (Virginia '16) was the only unseeded guy to win on Thursday after he overcame nine double faults to defeat Jared Hiltzik (Illinois '16) 6-4, 6-2, Shane managed to win 73% of the points on his serve (88% of the points when he got the ball in play) despite the double faults and sub 50% first serve percentage. Shane won 13 of 20 points on Hiltzik's second serve which played a large role in Shane breaking Hiltzik three times.
Shane will face Austin Smith (Georgia '16) after Smith defeated Georgia Tech junior Chris Eubanks 7-5, 6-1. Smith converted on three of four break points while Eubanks went zero for two.
Men's Draw - Quarterfinals
 Tom Fawcett (Stanford Jr) def. Konrad Zieba (Northwestern Sr) 3-6, 6-3, 6-0
 Austin Smith (Georgia '16) def. Chris Eubanks (Georgia Tech Jr) 7-5, 6-1
Ryan Shane (Virginia '16) def.  Jared Hiltzik (Illinois '16) 6-4, 6-2
Semifinals (1:30 p.m. ET)
 Thai-Son Kwiatkowski (Virginia Sr) vs.  Tom Fawcett (Stanford Jr)
 Austin Smith (Georgia '16) vs. Ryan Shane (Virginia '16)
Ronit Yurovsky (Michigan '16) avenged two regular season straight set losses to the top seed Ohio State sophomore Francesca Di Lorenzo by winning in straight sets herself. Yurovsky converted three of nine break points in the 6-4, 6-4 win and will now face Julia Elbaba (Virginia '16) in the semifinals.
Elbaba defeated North Carolina senior Hayley Carter 6-2, 6-1 in a match where both struggled with their service games. Carter had 15 break point chances but could only convert one while Elbaba went five of eight on break points. Elbaba won 58% of the points on her serve and Carter's serve while Carter won 42% on her serve and Elbaba's serve.
Breaunna Addison (Texas '16) won in three-sets over Florida junior Brooke Austin in a match where Addison broke Austin's serve nine times. Austin broke six times herself but it wasn't enough in the 6-7(5), 6-2, 6-4 defeat. Below comments are via Florida's website:
Ronit Yurovsky (Michigan '16) def.  Francesca Di Lorenzo (Ohio State Soph) 6-4, 6-4
Julia Elbaba (Virginia '16) def.  Hayley Carter (North Carolina Sr) 6-2, 6-1
 Breaunna Addison (Texas '16) def. Brooke Austin (Florida Jr) 6-7(5), 6-2, 6-4
 Danielle Collins (Virginia '16) def. Kennedy Shaffer (Georgia Jr) 6-1, 6-2
Semifinals (Noon ET)
Ronit Yurovsky (Michigan '16) vs. Julia Elbaba (Virginia '16)
 Danielle Collins (Virginia '16) vs.  Breaunna Addison (Texas '16)
Former Illini Rajeev Ram won the silver medal in mixed doubles at last month's Rio Olympics (w Venus Williams) and on Friday he'll compete for a US Open Mixed Doubles Championship as he and Coco Vandeweghe meet Mate Pavic and Laura Siegemund - first serve is scheduled for noon eastern on Arthur Ashe Stadium Court with the match being televised by ESPN2. It will also be streamed online at WatchESPN.
UCLA's incoming freshman Jada Hart and Ena Shibahara moved on to the doubles semifinals after defeating 2017 Georgia commit Morgan Coppoc and her partner Taylor Johnson 6-2, 6-3. Hart and Shibahara will face the No. 5 seeds Kaja Juvan and Iga Swiatek in the fourth match on Court 17.
Check out Zoo Tennis for more details/quotes from today's US Open Juniors.
US Open Junior
Boys' Singles Third Round
#128 [Q] Patrick Kypson def. #24 JJ Wolf ('17 Ohio State commit) 2-6, 6-3, 6-0
Boys' Doubles Quarterfinals
T Horie/Y Shimizu def. Nick Stachowiak (Duke Fr)/Sean Sculley ('17 Duke commit) 6-3, 2-6, 1-0 (2)
Z Bergs/Y Oliel def. Anthony Jackie Tang (Columbia Fr)/C Lo 6-7(0), 6-4, 1-0 (5)
Girls' Singles Third Round
#9  Sofia Kenin def. #71 [Q] Ashley Lahey (Pepperdine Fr) 4-6, 7-6(1), 6-3
Girls' Doubles Quarterfinals
Jada Hart/Ena Shibahara (UCLA Fr's) def. Morgan Coppoc ('17 Georgia commit)/Taylor Johnson 6-2, 6-3
Jada Hart/Ena Shibahara (UCLA Fr's) vs.  Kaja Juvan/Iga Swiatek