William Kjellberg
Generation
Born in 2009 (15-16 years old)
Year-end Junior World Ranking
Rival
Julian Theler (1-1)
- [2025] J30BELLINZONA 6-1 6-2
- [2024] J30VADUZ 3-6 4-6
Match Details
| W | 1R | Noel Kim Bachmann | 6-0 6-2 |
| W | 2R | Lorenzo Rocco | 6-2 6-3 |
| W | QF | Julian Theler | 6-1 6-2 |
| W | SF | Lorenzo Elia | 6-3 6-2 |
| W | F | Neil Saxer | 6-3 6-7 7-6 |
| L | 1R | Petar Ciangherotti | 6-2 4-6 4-6 |
| W | 1R | Lorenzo Sverzut Corsini | 6-2 6-1 |
| W | 2R | Daniel Joita | 6-2 6-2 |
| L | QF | Samuel Mandelkorn | 4-6 2-6 |
| W | 1R | Darsh Sachin Patel | 6-0 6-0 |
| L | 2R | Nikita Smirnov | 6-7 3-6 |
| W | 1R | Tiago Peterhans | 1-6 6-2 6-2 |
| W | 2R | Niccolo Crivelli | 6-4 6-2 |
| W | QF | Stepan Ziska | 7-6 7-5 |
| L | SF | Julian Theler | 3-6 4-6 |
| W | 1R | Emil Torn | 6-3 6-1 |
| W | 2R | Aarne Koskinen | 6-3 6-3 |
| W | QF | Nicolo Romano | 6-0 6-1 |
| W | SF | Krystof Vymazal | 7-5 6-4 |
| L | F | Leo Stenlund | 1-6 6-7 |
| L | 1R | Aleksandrs Sotikovs | 1-6 3-6 |
| W | 1R | Afan Nekovic | 6-4 6-3 |
| L | 2R | Todor Vukomanovic | 0-6 4-6 |
| W | 1R | Thomas Dixon | 6-2 6-1 |
| L | 2R | Brandon Ratanavong | 7-6 6-7 2-6 |
| L | 2R | Love Nyqvist | 2-6 6-4 0-6 |
| W | 1R | Alessandro Fiocchi | 6-1 6-4 |
| W | 2R | Mick Ilnicki | 6-7 6-1 6-2 |
| W | QF | Tristan Thomas Engelschmidt | 6-0 6-0 |
| W | SF | Lukas Andersson | 7-5 6-4 |
| L | F | Tim Malmqvist | 6-3 2-6 0-6 |
| W | 1R | Benjamin Scharner | 7-6 6-0 |
| L | 2R | Daniel Klocurek | 4-6 6-4 1-6 |
| W | 1R | Rasmus M Grindheim | 6-3 6-1 |
| W | 2R | Hartmut Fiedler | 6-1 6-0 |
| L | 3R | Sebastian Eie | 4-6 2-6 |
Junior Tennis Database is a site that summarizes the results of ITF junior tennis tournaments.
Number of registered tournaments: 5720, Number of registered players: 4,970, Number of registered results: 218,311