Right-back - Danilo (Juventus)
A squad player at both Real Madrid and Manchester City, Brazil's Danilo has featured consistently for Juventus since joining them in 2019.
The 29-year-old is a highly versatile player who can play in both full-back positions. Danilo is likely to be given a start against Peru in the Copa America 2021 semi-final ahead of Barcelona's Emerson Royal. The right-back's experience and passing ability could prove to be key in this game.
Danilo is a consistent performer at club level and was one of Juventus' better performers during the 2020-21 season. While he is no Dani Alves, the former Porto man is a solid player.
Centre-back - Eder Militao (Real Madrid)
Like the goalkeepers, Brazil boss Tite has often rotated his centre-backs at Copa America 2021, with Eder Militao, Thiago Silva and Marquinhos all getting minutes.
It was Marquinhos and Thiago Silva who started against Chile in the quarter-final, so it would not be surprising to see Militao handed another opportunity in the semi-final. The 23-year-old has not set a foot wrong at Copa America 2021 thus far and is getting better with every performance.
Militao is likely going to start for Real Madrid next season at centre-back following the departure of Sergio Ramos and the possible exit of Raphael Varane. A strong end to the Copa America 2021 would do wonders to his confidence.
Centre-back - Marquinhos (Paris Saint-Germain)
Marquinhos is one of the best centre-backs in the world at the moment, and has proved his worth for club and country time and time again.
Since joining Paris Saint-Germain in 2013, Marquinhos has gone from strength to strength. The 27-year-old had a good mentor in Paris in Thiago Silva. Since the latter's departure, Marquinhos has taken over the role of a senior statesman. In recent seasons, the Brazil international has produced some excellent performances in defensive midfield as well.
At Copa America 2021, Marquinhos has been a key player for Brazil. The former Roma man has also been appreciated for his leadership ability, and will be key in the semi-final against Peru.
Left-back - Renan Lodi (Atletico Madrid)
Atletico Madrid won the La Liga title last season, but Renan Lodi made only 11 starts in the league for Diego Simeone's side.
He did start against Chile in the quarter-final of Copa America 2021, ahead of Juventus' Alex Sandro. The 23-year-old, who has made 76 appearances in all competitions for Atletico Madrid since joining them in 2019, will hope to get more minutes under his belt after a frustrating season.
Lodi is incredibly talented and has been linked with a move away from Atletico Madrid in recent weeks. A strong showing in the Copa America 2021 semi-final will help him attract interest.
Other options: Emerson Royal (Barcelona), Thiago Silva (Chelsea), Leo Ortiz (Red Bull Bragantino), Alex Sandro (Juventus).