| Challenger Braga | 09/26 14:00 | 25 | [351] Gastao Elias v Alessandro Giannessi [215] | 6-7,4-6 | |
| Challenger - Sibiu | 09/19 10:20 | 25 | Bor Artnak v Alessandro Giannessi | Retired | |
| Challenger - Sevilla | 09/07 19:00 | 27 | [244] Alessandro Giannessi v Hugo Gaston [99] | 6-3,1-6,0-6 | |
| Challenger - Sevilla | 09/06 09:00 | 26 | [244] Alessandro Giannessi v Daniel Rincon [228] | 7-6,6-0 | |
| Challenger - Sevilla | 09/04 19:50 | 25 | [82] Jaume Munar v Alessandro Giannessi [244] | 7-6,3-6,4-6 | |
| Challenger - Como | 08/31 10:30 | 26 | [244] Alessandro Giannessi v Rudolf Molleker [232] | 3-6,1-6 | |
| Challenger - Como | 08/29 09:00 | 25 | [199] Jelle Sels v Alessandro Giannessi [244] | 2-6,2-6 | |
| US Open | 08/24 14:00 | 15 | [245] Alessandro Giannessi v Giulio Zeppieri [137] | 3-6,4-6 | |
| US Open | 08/22 17:45 | 14 | [245] Alessandro Giannessi v Harold Mayot [211] | 7-6,7-5 | |
| Challenger - San Marino | 08/02 11:00 | 26 | [234] Federico Delbonis v Alessandro Giannessi [235] | 6-3,5-7,6-1 | |
| Challenger - San Marino | 07/31 17:00 | 25 | [235] Alessandro Giannessi v Moez Echargui [291] | 1-6,6-4,6-4 | |
| Challenger - Trieste | 07/18 13:50 | 25 | [348] Stefano Napolitano v Alessandro Giannessi [235] | 6-4,6-2 | |
| Challenger - Trieste | 07/18 08:00 | 25 | Franco Agamenone v Alessandro Giannessi | Cancelled | |
| Challenger - San Benedetto | 07/11 14:50 | 25 | Alessandro Giannessi v Luciano Darderi | Cancelled | |
| Challenger - Milan | 07/05 08:30 | 26 | [216] Gauthier Onclin v Alessandro Giannessi [241] | 6-4,6-1 | |
| Challenger - Milan | 07/03 13:00 | 25 | [241] Alessandro Giannessi v Francesco Maestrelli [149] | 6-3,3-6,6-1 | |
| Wimbledon | 06/26 13:05 | 14 | [235] Alessandro Giannessi v Charles Broom [374] | 4-6,7-6,3-6 | |
| Challenger - Parma | 06/22 11:00 | 27 | [254] Alessandro Giannessi v Alexandre Muller [103] | 6-3,3-6,1-6 | |
| Challenger - Parma | 06/21 10:30 | 26 | [254] Alessandro Giannessi v Oriol Roca Batalla [306] | 6-4,6-2 | |
| Challenger - Parma | 06/20 13:30 | 25 | [304] Maxime Janvier v Alessandro Giannessi [254] | 4-6,6-4,1-6 | |
| Challenger - Parma | 06/20 13:30 | 25 | Fabian Marozsan v Alessandro Giannessi | Cancelled | |
| Challenger - Perugia | 06/12 16:00 | 25 | [251] Matteo Gigante v Alessandro Giannessi [238] | Retired | |
| ATP - Geneva | 05/21 11:20 | 19 | [230] Alessandro Giannessi v Vitaliy Sachko [282] | 5-7,2-6 | |
| ATP - Geneva | 05/20 11:30 | 14 | [230] Alessandro Giannessi v Denis Yevseyev [296] | 3-6,6-4,6-2 | |
| Challenger - Oeiras | 05/16 10:10 | 25 | [179] Jan Choinski v Alessandro Giannessi [230] | 6-3,4-6,6-4 | |
| Challenger - Oeiras | 05/15 09:00 | 19 | [230] Alessandro Giannessi v Daniel Michalski [289] | 6-4,6-4 | |
| Challenger - Oeiras | 05/14 10:25 | 14 | [230] Alessandro Giannessi v Alberto Barroso Campos [452] | 6-1,6-3 | |
| Challenger - Francavilla | 05/10 11:20 | 26 | [160] Benoit Paire v Alessandro Giannessi [230] | 7-5,7-5 | |
| Challenger - Francavilla | 05/09 09:00 | 25 | [230] Alessandro Giannessi v Marco Trungelliti [227] | 3-6,6-3,6-4 | |
| Challenger - Cagliari | 05/04 11:45 | 26 | [246] Alessandro Giannessi v Thanasi Kokkinakis [111] | 4-6,2-6 |
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.