Benteke, absent for Villa's last three games due to a knee problem, trained on Monday ahead of the Barclays Premier League trip to the Stadium of Light.
The Belgium striker scored three goals in a 6-1 home league win against the Black Cats in April - among the 15 he netted for the midlands outfit in all competitions between January 1 and the end of 2012/13, and a total of 23 over the course of what was a stand-out debut campaign in English football.
Things have gone less well for Benteke so far in 2013/14, though, with the five goals he notched in his first five Villa matches this term being the only ones he has to date for the season.
Giving an update on the frontman - who has failed to find the net in the last 10 games he has played for Villa - Lambert said: "Christian trained this morning and looked okay.
"He feels okay within himself. The thing with Christian is he's a young guy, and people forget that.
"Everyone put this super-stardom thing on him, but he's 23 years of age.
"He's a young guy and his confidence suffers, as everyone else's does.
"He's back and hopefully he will do what he did at the tail-end of last season.
"This is the point where Christian scored all his goals and if he does all that, it would be great."
Villa captain and defender Ron Vlaar, who has been out for five games due to a calf injury, did some light training on Monday morning and may also be set to make his comeback in the Sunderland contest.
That would be particularly timely, with fellow centre-back Ciaran Clark suspended having picked up his fifth booking of the season last time out.
Another defender, Joe Bennett, is also on the road to recovery following a long spell on the sidelines with a back injury.
Villa have not won any of their last five games, losing four of them, and the 1-1 draw against Swansea on Saturday meant they have taken just eight points from 10 home fixtures this season.
But Lambert, whose side head into the match against rock-bottom Sunderland lying 13th in the table, insists there should not be "doom and gloom" about how Villa are currently faring.
"We are only three points off 10th so it is not doom or gloom," Lambert said.
"It's how people want to portray it. I've never been a negative person."
He added: "If you look at the table, we are sitting in a pretty decent position. We are ahead of where we were last year.
"Ideally, we want to play better, there's no two ways about it.
"But it was important we stopped the sequence (of four successive defeats) on Saturday - that was absolutely paramount, that we stopped our losing run.
"We have to have everyone fit, and hopefully one or two are coming back.
"We are three points behind 10th, which is incredible.
"The great thing about the Swansea game was after Boxing Day (when Villa lost 1-0 at home to Crystal Palace) they came out and a young side did not capitulate.
"They kept going and had a great desire not to get beat. If you can't win it, it is important not to lose it.
"I can understand everyone's apprehension after the Crystal Palace game.
"They are a young side but they never wilted, which can happen, and that was impressive."