Benteke suffered a hip flexor injury during Villa's 1-0 win over Norwich City on Saturday and had to be substituted immediately.
Initial tests suggested the 22-year-old could be out for up to six weeks, however Lambert revealed he was recovering quiker than expected.
"He is doing great and I think he will be back quicker," he told the club's official website. "He is doing really fine now and seems a lot happier within himself.
"We just have to wait and see. We've got two games before the international break.
"The international break has probably come at the right time for him and for us and he is doing great at the minute.
"The worst fear was that he was going to be out for considerable time but the way he is progressing, I think everybody is pretty happy."
