| 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 Prague | 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 | |
| Challenger Vicenza | 05/31 07:30 | 26 | [164] Alessandro Giannessi v Adrian Menendez-Maceiras [150] | 6-2,6-0 | |
| Challenger Vicenza | 05/30 10:55 | 25 | [164] Alessandro Giannessi v Federico Gaio [202] | 6-3,6-2 |
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.