Having missed the first three league matches, due to receiving his Italian passport, He was an immediate success, scoring on his debut at the Stadium of Light against West Ham United. Arca then helped the side in defence kept four consecutive clean sheets throughout October. The following month, he only played three matches, including scoring against Manchester United, due to his international commitment with Argentina U20. Arca's third goal of the season came on 1 January 2001, in a 4–1 win over Ipswich Town. However, he missed five matches throughout January because of his continuous international commitment with Argentina U20. It wasn't until on 10 February 2001 when Arca made his return to the first team, in a 1–1 draw against Liverpool. Arca played for his previous club and national team at left-back, but was successfully converted to left midfield by Reid. Arca scored three times in thirty appearances for the Black Cats in his first season in the Premiership. For his performance, he won the club's Young Player of the Year award. Arca also became a fan favourite among Sunderland supporters.