The south coast club will play the first leg of their Europa League qualifier against Vitesse Arnhem on Thursday.
Fonte has claimed that leading the club, who just four years ago were in League One, will be one of the greatest moments of his career.
"It's definitely one of the proudest moments in my career," he said.
"We have been together for a long time and through all the dark, tough years, and now to be leading the team will be a very proud moment.
"I am extremely happy and want the game to come as soon as possible."