Defender Carlos, the club’s big summer signing from Sevilla, limped off late on at Villa Park.
“I’m extremely worried about that situation,” said Gerrard in his post-match press conference. “We’re going to send him for an MRI scan but it doesn’t look good.
“I’m extremely happy with the win and the performance but, if we happen to lose someone who’s so important to us, that could tarnish the win.
“It’s around the ankle, Achilles area. He felt an awkward mechanism in there. You can see by the player and the man that he’s not the type to go off easy. He looks concerned about it and the medical staff seem concerned and that’s the reason why I’m worried about it.”
Villa can expect to be without the 29-year-old Brazil international for much of the season.
A statement from the club read: “Aston Villa can confirm Diego Carlos has ruptured his Achilles tendon. The player will require surgery and will then begin his rehabilitation programme.”
Carlos’ performances for Sevilla last season made him a sought-after talent but it was Villa who won the race for his signature, announcing the deal in May.
The centre-back settled well into the side and to lose him after only two competitive appearances for the club is a major blow that could affect Villa’s plans for the rest of the transfer window.