On a day when numerous top seeds perished, Aidan Kim of the United States could perhaps lay claim to the biggest Junior Championships, Wimbledon giant-killing after dispatching junior world No. 3 Gabriel Debru.

Kim, who navigated qualifying to take his place in the main draw here, mounted a gutsy recovery, fighting back from a set down to prevail 4-6 6-3 6-3 and set-up a third-round showdown with fellow countryman Michael Zheng.

Kim and Zheng are well-acquainted and train together at the USTA campus in Orlando, although Kim will head into the clash in buoyant mood and with a new-found confidence following his downing of top seed Debru.

After all, Debru was bidding to become the first boy to win back-to-back Junior Grand Slam titles – and indeed the Roland Garros-Wimbledon double – since Tseng Chun-Hsin of Chinese Taipei in 2018 after conquering all before him in Paris last month.

That is the level of Kim’s accomplishment and even speaking a couple hours after leaving court to much fanfare from a crowd favouring the underdog, the scale of his achievement had yet to fully sunk in.

“It still needs to settle in a little bit more, but it feels amazing because I haven’t beaten a top 10 player before and to beat someone who is a Junior Grand Slam champion is incredible,” junior world No.63 Kim told itftennis.com. “It was the best I’ve ever felt on court and a breakthrough moment.

“This win is a massive confidence-booster and gives me huge belief going forward. At the present time, however, I am just enjoying the moment, it is an unforgettable experience and, quite honestly, I am still just happy to be here.

“In fairness, I have always believed I can win any match I play, and I came into the Junior Championships with a positive attitude, but with minimal expectations as I just wanted to enjoy the moment. That is exactly what I am doing.

“I knew I was the underdog today, but since I got here [Kim contested J1 Nottingham in the build-up to Wimbledon], I feel like I have been considered the underdog. I enjoyed being the underdog today.”

Debru was not alone in suffering a surprise defeat as three other highly fancied players fell by the wayside. The first was No. 2 seed Jakub Mensik, who reached the boys’ final at January’s Australian Open, another high-profile casualty.

Mensik succumbed 6-3 6-4 to Spain’s Pedro Rodenas, who will now draw swords with Slovenia’s Bo Artnak – a member of the Grand Slam Development Programme/ITF Touring Team – following his hard-fought victory over American Alexander Frusina.

No. 4 seed Gonzalo Bueno was another high-ranked player to bow out, slipping to a 6-4 3-6 3-6 defeat against Learner Tien of the United States, with a total of four Americans making the third round following Sebastian Gorzny’s triumph over 15-year-old Brazilian Joao Fonseca.

That number would have been greater but for Nishesh Basavareddy coming unstuck against Slovakian Peter Privara, who will now go head-to-head with Hong Kong’s Coleman Wong. The 18-year-old overpowered Croatia’s Dino Prizmic to advance to round three.

Pirzimic's fellow Croatian Mili Poljicak is now the highest-ranked player remaining in the boys’ draw after he bucked the trend and avoided any slip-ups with victory against Canada’s Jaden Weekes.

It also proved a successful day for Spain’s Martin Landaluce, who chalked up his 13th successive match-win on grass to dispatch Australia’s Ed Winter and set-up a showdown with Belgium’s Gilles Arnaud Bailly for a place in the quarter-finals.

Poland’s Martyn Pawelski, Switzerland’s Kilian Feldbausch, Lithuanian Edas Butvilas, Belgium’s Alexander Blockx and Kalin Ivanovski of North Macedonia also progressed.