The 28-year-old midfielder completed a move from Juventus in July after spending his entire career in Italy, and he is delighted with how pre-season has gone in his new surroundings.
The Italian featured in Sunderland's recent tour of Asia, but he insists he can improve his fitness levels.
"It has been two good weeks and I came here with a lot of excitement. I am going to give my best of myself to the gaffer," he told the club’s official website.
"Because I played in the Confederations Cup I did not have much time to rest with only ten days’ holiday. But I still made myself available straight away for the team.
"I first met my team in Peschiera del Garda and we have had a good pre-season. I am still not 100% fit, but we will work toward this."
The addition of the Italy international is just one of eight new arrivals for the Premier League side during the current transfer window, with Jozy Altidore, Vito Mannone and Cabral among them.
And Paolo Di Canio's side are already reaping the benefits having beaten Tottenham 3-1 in the Asia Trophy before losing 1-0 to Manchester City in the final.
Sunderland, who finished 17th last term, begin the new season against Fulham at home on August 17.