The Brazil international fell out-of-favour under manager Ruben Amorim this season and he was loaned out to Real Betis in January.
Antony has found his feet at Betis with four goals and four assists from 12 games. His performances have caught the eye of Atletico.
The La Liga giants are preparing a formal approach this summer. United are confident that they can secure at least £40 million from his exit.
Antony was signed for a staggering £85 million three years ago. The Red Devils seem prepared to cut their losses on him this summer.
There were no serious suitors for the attacker at the start of the season, but his loan stint at Betis could pave the way for a reasonable deal.
The Red Devils could focus on signing a new right wing-back with the funds recouped from Antony's potential move to Atletico.