The Citizens were keen to recruit a central striker over the summer, following the departure of club legend Sergio Aguero, but were unable to sign their primary target Harry Kane, who stayed with Tottenham Hotspur.
City struggled to find the net against Southampton last weekend, however Nunez was in red-hot form, scoring a brace for the second successive match in their 3-1 league victory over Boavista on Monday night.
The 22-year-old, who joined Benfica from Spanish outfit Almeira in September 2020, scored 14 goals and provided 12 assists in 44 appearances across all competitions during his first season with the Primeira Liga club.
City have history with recruiting players from Benfica in recent years, after signing goalkeeper Ederson from the Portuguese giants in 2017 as well as defender Ruben Dias last summer. body check tags ::