LONDON, UK - Wildcard Cori Gauff continues to rack up youthful milestones, upsetting No.1 seed Aliona Bolsova 6-3, 6-4 on her Wimbledon qualifying debut.

The 15-year-old American's win over the World No.94 makes her the youngest player to defeat a Top 100 player at a Grand Slam since a 14-year-old Martina Hingis's run to the fourth round of the 1995 US Open. Gauff, the 2018 Roland Garros junior champion, displayed impressive composure as well as effortless power, serving out both sets from 0-40 down against an opponent fresh off a fourth-round run in Paris who never seemed at ease on the grass.

Afterwards, the World No.301 revealed that she had approached the match with confidence but no expectations. "I'm the underdog, she's the top seed," Gauff pointed out. "But no matter who I play, I think I can win." Having suffered from nerves on her Roland Garros debut last month, Gauff said that she felt more relaxed today - not least because her mind "wasn't on the court". Instead, her pre-match playlist, which includes Jaden's 'Icon' and Lil Nas X's 'Old Town Road', was stuck in her head throughout.

Another former junior standout turning heads was Youth Olympic Games gold medallist and No.20 seed Kaja Juvan, Gauff's conqueror in Paris, who won an early-evening epic 6-4, 3-6, 10-8 over Valentini Grammatikopoulou. The 18-year-old Slovenian missed three match points at 7-6, but screamed in delight as her Greek opponent went long on her sixth. "I don't know how I did it," gasped Juvan afterwards as she collapsed into best friend Iga Swiatek's arms - a repeat of what had happened after the duo won the Youth Olympic Games doubles gold together last October in Buenos Aires.

Juvan, a keen reader of psychology and philosophy who is a particular fan of Socrates and Descartes, made her Grand Slam main draw debut in unusual circumstances at Roland Garros - given two hours' notice before having to play on Court Suzanne-Lenglen as a lucky loser following Petra Kvitova's withdrawal. She says that "nerves got the better of me" in that match, which she lost 2-6, 7-5, 7-5 to Sorana Cirstea - but that the experience had helped her succeed today.

Elsewhere, 2018 Australian Open junior champion Liang En-Shuo battled a home crowd firmly behind talented 16-year-old home wildcard Emma Raducanu, edging a tight first set before easing away 7-6(4), 6-2. The 18-year-old from Chinese Taipei had interrupted her grass season midway through to compete in Fed Cup Group II zonal play in Tajikistan two weeks ago, but showed no ill effects  in a performance of high-risk shotmaking that was particularly impressive given her size.

"I'm short, so I have to hit the ball hard to win more easily," the five-foot-two Liang, a fan of singer Jay Chou, explained afterwards. Indeed, her height was an advantage on grass: "I know the ball is very low - but it's good for me because I'm low as well," she laughed. "I don't need to bend my knees as much!"

In more good news for the group of teenagers surging towards the main tour, 17-year-old Catherine McNally - runner-up to Gauff in the 2018 Roland Garros juniors, and her partner to win the US Open girls' doubles title last year - displayed a mature and creative game style to squeeze past former World No.32 Kurumi Nara 7-6(4), 7-6(2). The American, who showcased excellent use of the slice and conjured up a delightful dropshot-lob combination en route to winning the second tiebreak, says that she enjoys playing "with imagination" - and is inspired by the success of World No.1 Ashleigh Barty. "That just shows you, when she slices, she can throw off all the players," said McNally. "A lot of girls don't like that."

Meanwhile, 18-year-old US Open junior champion and No.21 seed Wang Xiyu progressed 7-5, 6-3 in a serve-dominated contest against Georgina Garcia Perez, while 18-year-old Moscow River Cup winner and No.14 seed Olga Danilovic harnessed her power at key moments to edge out wildcard Eden Silva 6-4, 7-6(2). However, 17-year-old No.9 seed Whitney Osuigwe was upset 4-6, 7-5, 6-3 by Moldova-born Spaniard and Grand Slam qualifying debutante Cristina Bucsa, while 16-year-old Marta Kostyuk was unable to hit through No.30 seed Anna Kalinskaya, falling 6-1, 7-5.

Former Wimbledon finalist Sabine Lisicki made a sudden return to form back on her beloved London lawns, too. The German, runner-up to Marion Bartoli in 2013, came into the tournament with just a 2-12 win-loss record in 2019 and a ranking of World No.283 - but made good use of her wildcard to upset No.27 seed Timea Babos 6-3, 3-6, 6-3. But another former Top 20 player's poor season continued as Peng Shuai was eliminated by local wildcard Samantha Murray 6-4, 6-7(5), 6-4, falling to 1-8 in 2019. The No.362-ranked Briton thrilled an enthusiastic home crowd by peaking in the closing stages of the match, breaking the 2014 US Open semifinalist in the last game with a brilliant half-volley pickup and a clean backhand return winner on match point.

There was an encouraging return to the Grand Slam stage for 2015 Baku finalist Patricia Maria Tig following maternity leave. The Romanian has based herself in Cancun for a series of ITF W15 events this year to kick off her comeback, compiling a 25-6 record including two titles, and pushed No.22 seed Paula Badosa all the way before falling 3-6, 6-1, 6-4.

Arina Rodionova won the longest match of the first day, triumphing 7-6(6), 6-7(2), 8-6 over Asia Muhammad in three hours and seven minutes, while No.3 seed Lauren Davis was forced to save one match point before overcoming Bibiane Schoofs 1-6, 7-6(3), 6-4. However, there were smoother passages for No.2 seed Anna Blinkova over Zoe Hives 6-1, 7-5 and fast-rising No.8 seed Elena Rybakina over Ellen Perez 6-1, 6-4, while Nottingham quarterfinalist Elena-Gabriela Ruse - who held six match points against Agnieszka Radwanska in last year's main draw before losing a thriller - dismissed Sesil Karatantcheva 6-2, 6-2.