| Challenger Florence | 09/25 13:55 | 25 | [381] Jules Okala v Alessandro Giannessi [168] | 3-6,0-6 | |
| Challenger - Biella | 09/20 12:50 | 27 | [108] Alejandro Davidovich Fokina v Alessandro Giannessi [171] | 6-2,6-1 | |
| Challenger - Biella | 09/19 14:10 | 26 | [196] Marco Trungelliti v Alessandro Giannessi [171] | 6-7,1-6 | |
| Challenger - Biella | 09/17 10:10 | 25 | Giacomo Dambrosi v Alessandro Giannessi | 4-6,4-6 | |
| Challenger - Szczecin | 09/11 11:10 | 25 | Pawel Cias v Alessandro Giannessi | 6-2,6-0 | |
| Challenger - Genova | 09/02 11:25 | 24 | [150] Alessandro Giannessi v Viktor Galovic [224] | Retired | |
| Challenger - Como | 08/31 12:10 | 28 | [266] Facundo Mena v Alessandro Giannessi [150] | 6-2,1-6,6-2 | |
| Challenger - Como | 08/30 13:20 | 27 | [150] Alessandro Giannessi v Dmitry Popko [236] | 7-6,4-6,6-4 | |
| Challenger - Como | 08/29 13:25 | 26 | [150] Alessandro Giannessi v Sebastian Ofner [167] | 6-4,6-2 | |
| Challenger - Como | 08/28 08:00 | 25 | [150] Alessandro Giannessi v Johan Tatlot [343] | 1-6,6-4,6-3 | |
| US Open | 08/22 16:25 | 45 | [201] Constant Lestienne v Alessandro Giannessi [149] | 6-3,6-0 | |
| US Open | 08/20 15:00 | 44 | [278] Jeffrey John Wolf v Alessandro Giannessi [149] | 6-2,5-7,2-6 | |
| Challenger Sopot | 07/30 13:25 | 25 | Alessandro Giannessi v Aleksandre Metreveli | 6-4,3-6,4-6 | |
| Challenger - Prag | 07/24 10:35 | 25 | [152] Alessandro Giannessi v Andrea Collarini [313] | 0-6,2-6 | |
| Challenger - San Benedetto | 07/21 19:15 | 29 | [163] Alessandro Giannessi v Renzo Olivo [330] | 7-5,6-7,4-6 | |
| Challenger - San Benedetto | 07/20 17:55 | 28 | [119] Andrej Martin v Alessandro Giannessi [163] | 7-6,1-6,6-7 | |
| Challenger - San Benedetto | 07/19 17:45 | 27 | [163] Alessandro Giannessi v Andrea Arnaboldi [219] | 5-7,6-3,7-6 | |
| Challenger - San Benedetto | 07/18 17:30 | 26 | [163] Alessandro Giannessi v Manuel Guinard [346] | 6-3,4-6,6-3 | |
| Challenger - San Benedetto | 07/17 19:15 | 25 | Alessandro Giannessi v Christopher O'Connell | 7-6,6-3 | |
| Challenger - Perugia | 07/12 17:00 | 27 | [160] Alessandro Giannessi v Albert Ramos-Vinolas [99] | Retired | |
| Challenger - Perugia | 07/11 11:50 | 26 | [160] Alessandro Giannessi v Facundo Bagnis [161] | Retired | |
| Challenger - Perugia | 07/09 10:20 | 25 | [160] Alessandro Giannessi v Mario Vilella Martinez [269] | 6-7,6-2,6-3 | |
| Wimbledon | 06/24 14:15 | 44 | [213] Yannick Hanfmann v Alessandro Giannessi [163] | 7-5,7-5 | |
| Challenger - Parma | 06/19 10:05 | 25 | [370] Julian Lenz v Alessandro Giannessi [162] | 6-1,6-4 | |
| Challenger - Poznan | 06/07 09:30 | 27 | [395] Andrea Vavassori v Alessandro Giannessi [164] | 7-6,6-1 | |
| Challenger - Poznan | 06/06 11:10 | 26 | [164] Alessandro Giannessi v Daniel Masur [251] | 7-6,4-6,6-3 | |
| Challenger - Poznan | 06/05 12:20 | 25 | [164] Alessandro Giannessi v Sumit Nagal [280] | 7-5,3-6,6-3 | |
| Challenger - Vicenza | 06/02 13:00 | 29 | [164] Alessandro Giannessi v Filippo Baldi [163] | 7-5,6-2 | |
| Challenger - Vicenza | 06/01 14:00 | 28 | [142] Gianluca Mager v Alessandro Giannessi [164] | 3-6,3-6 | |
| Challenger - Vicenza | 05/31 11:25 | 27 | [185] Marc Polmans v Alessandro Giannessi [164] | 4-6,5-7 |
Alessandro Giannessi (born 30 May 1990) is a professional Italian tennis player. On 24 July 2017 he reached his highest ATP singles ranking of world No. 84 while his best doubles ranking was No. 171 on 14 October 2013.
Giannessi made his Grand Slam debut at the 2016 US Open as a qualifier where he recorded his first Major win defeating Denis Kudla in five sets.
Giannessi was a singles semifinalist at the 2017 Croatia Open Umag.
At the 2021 French Open he made his debut at this Major after qualifying for the main draw with a win over Francisco Cerundolo.
At the 2022 French Open although he lost in the third round of qualifying to Sebastian Ofner he entered the main draw as a lucky loser.
He won his fourth Challenger title and first since 2019 at the 2023 Zadar Open this time with a win over Sebastian Ofner.