Grealish made his England debut last month and Smith believes his form for Villa means he should be considered once again.
Speaking after his team's 3-0 win over Fulham - in which Grealish scored - when asked if the midfielder could do anything more to convice Southagte, Smith said: "He certainly couldn't. That'll be Gareth's decision but Jack can't do any more.
"I thought it was a terrific performance. Certainly the first half. Not just the goal and the assist for the second goal, but defensively as well.
"He gave a couple of cross-field balls away but his reaction to go and defend and get behind the ball to win it back was excellent. It's something he's added to his game along with the breakthrough run he made for the goal."
Fulham coach Scott Parker has seen his team lose all three matches so far and believes that they need signings if they are to compete in the top-flight.
He said: "We need to work out whether we want to compete or otherwise it will be a tough year. This team needs to evolve.
"This team needs to get better and get stronger. To do that we need to get players in. That's going to give us the chance to be successful.
"If not we'll work like we have worked and we'll try to improve things and try to keep pushing along."