In a surprising twist, the Red Devils pulled out of the deal at the last minute, opting instead to sign Belgian youngster Senne Lammens from Royal Antwerp.
The switch also facilitated Andre Onana’s loan move to Trabzonspor, leaving Martinez stuck in Birmingham but he responded in style, delivering a sensational display that earned Emery’s admiration.
"I am so, so happy. We need him. We struggled in his situation, but we have to get our feelings together and feel the collective objective,” Emery told Sky Sports.
“Today, his comeback has been fantastic. We have to protect him and feel him inside the group so he is comfortable and confident. He was fantastic.”
Attention now turns to midweek, as Aston Villa gear up for a challenging English Football League Cup third-round clash against Brentford.