He spent much of last season deputising for first-choice striker Fernando Torres, who was sidelined for long periods through injury, as Liverpool struggled to a disappointing seventh-place finish in the Premier League.
"The club had a difficult season last year but I want to prove we can get back into the top four. I am confident about this," added Ngog.
"My confidence is good. Now I have to do my job and give my best for the team."
Former Liverpool youth team captain Jay Spearing feels this could be a pivotal season for him at Anfield as well, after spending the latter part of last season on loan at Leicester.
"With a new manager coming in I have thought this could be my chance to break in and become a solid part of the first-team squad and be regularly involved," said Spearing, also 21.
"Obviously, at the end of the day it's down to me whether that happens. If that comes, then it comes. But if not, then we'll look at my options.
"But I want to break into Roy's plans; I want to be involved and playing more games this season."
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