The Reds are currently top of the Premier League and are yet to concede a goal.
The former German international believes that they will improve, not least with the return of Luis Suarez.
"They've given themselves a chance now," Hamann told FourFourTwo. "Top of the league, not conceded a goal yet.
"With Suarez coming back, you expect him to score more goals. If they keep the defence as tight as they did, I think a top-four position should be a very realistic target.
"If they improve the way they have over the last 12 months, I wouldn't rule out that Liverpool is a competitor for the Premier League title again in the next four or five years."
Liverpool's next game is a trip to Swansea City on September 16.