Question: What was the nickname of the current Italian football manager who played for A.C. Milan with Stefano Nava?

Context paragraphs:
Giovanni Trapattoni: Giovanni Trapattoni (] ; born 17 March 1939), sometimes popularly known as "Trap" or "Il Trap", is an Italian football manager and former footballer, considered the most successful club coach in the history of Serie A.  A former defensive midfielder, as a player he spent almost his entire club career with A.C. Milan, where he won two Serie A league titles (1961–62 and 1967–68), and two European Cups, in 1962–63 and 1968–69.  Internationally, he played for Italy, earning 17 caps and participating in the 1962 FIFA World Cup in Chile.

Alessandro Costacurta: Alessandro "Billy" Costacurta (born 24 April 1966) is an Italian football manager and a former professional defender, who usually played as a centre back.

Gennaro Gattuso: Gennaro Ivan "Rino" Gattuso, (] ; born 9 January 1978) is an Italian football manager in charge of A.C. Milan Primavera and a former footballer.

Stefano Nava: Stefano Nava (born 19 February 1969 in Milan) is an Italian former footballer, who played as a defender.  He is best known for having played for A.C. Milan in the early 1990s, where he was a backup for players such as Franco Baresi, Paolo Maldini, Mauro Tassotti and Alessandro Costacurta.

List of A.C. Milan honours: This is a list of A.C. Milan honours.  A.C. Milan is an Italian football club and this page contains historical and current trophies pertaining to the club.

Luciano Alghisi: Luciano Alghisi (born 18 April 1917) was a professional Italian football player.  He was born in Milan.  He played for 5 seasons (97 goals, 19 goals) in the Serie A for A.S. Roma, A.S. Bari and A.C. Liguria.  On his debut in Serie A for Roma, he scored a winning goal in a 1–0 victory over A.C. Milan.

Giorgio Morini: Giorgio Morini (born 11 October 1947) is an Italian former football manager and player, who played as a midfielder.  As a player, Morini was part of the A.C. Milan team that won the 1978–79 Serie A title.  He also coached the Italian football team Milan for part of the 1996–97 season.

Pietro Paolo Virdis: Antonio Pietro Paolo Virdis (born 26 June 1957) is an Italian football manager and former player, who played as a forward.  Throughout his career, he played for Nuorese, before playing in Serie A with Cagliari Calcio, Juventus F.C., Udinese Calcio, and A.C. Milan; he ended his career with Lecce.  Known for his eye for goal, with Juventus, he won two league titles and a Coppa Italia; with Milan, he was the league's top-scorer in 1987, also winning a league title and the Supercoppa Italiana in 1988, and was part of the club's European Cup victory in 1989.  At international level, he represented the Italy under-23 side at the 1988 Summer Olympics, helping the team to a fourth-place finish.

A.C. Milan (Superleague Formula team): A.C. Milan Superleague Formula team is the racing team of A.C. Milan, a football team that competes in Italy in the Serie A.  The A.C. Milan racing team competes in the Superleague Formula.

Demetrio Albertini: Demetrio Albertini (born 23 August 1971 in Besana in Brianza) is the sporting director of Parma and a former professional Italian football midfielder and vice-president of the Italian Football Federation (FIGC).  He is widely considered as one of the legends of the A.C. Milan side of the 90s and a fundamental player for the Italian national team of the same period.  He spent most of his career with Milan of the Italian Serie A, winning many trophies, including five Serie A titles and two UEFA Champions League titles with the club.  He also played his final season for FC Barcelona, winning the Spanish League before retiring that year.

Supporting paragraphs: Stefano Nava Alessandro Costacurta
Answer: Billy