The Anfield legends say their club must strengthen in the summer if they are to compete at the top of the Premier League.
Manager Brendan Rodgers went on a large recruitment drive in the summer after the sale of Luis Suarez to Barcelona, bringing in the likes of Adam Lallana, Dejan Lovren, Lazar Markovic and several others for large fees.
However, a poor start to the season saw them languishing at the wrong end of the table before a superb run of form left them challenging for the Champions League places with rivals Manchester United.
Despite that, they have naturally fallen short of the standards they set last year when they finished second behind eventual winners Manchester City, and their legends believe strong investment is needed to bring the title back to Anfield.
"The honest answer is that you want them to strengthen everywhere," said Fowler.
"If you look at the money Chelsea and Manchester City have, it gets harder and harder to win the league every year. If they sign any players, that makes them a bit stronger so you have to keep on their coat-tails."
Rush concurred with the thoughts of Fowler, saying that his old side must look to improve again in the summer if they wish to challenge for the title.
He does however back manager Rodgers and his young squad to end the club’s 25-year wait for the title sooner rather than later, especially given how close they came last season.
"They've got a young squad and I think if they look to improve in the summer - I think Brendan is doing a good job - and it has to happen sooner rather than later," added the club's record goalscorer.