The Red Devils have played without a fit left-back since the start of the season. Luke Shaw and Tyrell Malacia have been on the sidelines with injuries, but they are expected to return soon.
Despite this, new manager Ruben Amorim has his sights on landing a new left-back and Caught Offside claim that Chilwell is one of the top names under the consideration of the United hierarchy.
Chilwell has been deemed surplus to requirements by the Blues and he could be permitted to leave on loan with an option to purchase.
Meanwhile, Carreras only left the club for Benfica on a permanent deal last summer, but United have the option to re-sign him in January.
There is a low buy-back clause in the region of £17m and United could trigger the clause. Whoever is signed is likely to play as a wing-back.
Amorim is expected to operate with a 3-4-2-1 formation at United.
