Lewandowski, who worked under Klopp at Borussia Dortmund, expected Liverpool to challenge Pep Guardiola's Manchester City in the title race.
"Under Klopp I think they (Liverpool) will be fighting for the title this season. Pep and Manchester City will not make it easy for anybody to win the title, but Liverpool have a real chance," Lewandowski told British media.
"Without European football it can really help them with being fresh for games and with injuries and, even though Klopp is always smiling, he is ruthless enough to take advantage of that."
Poland international Lewandowski felt the Merseyside club were already benefiting from Klopp, who twice led Borussia Dortmund to the Bundesliga title and also to the final of the Champions League.
"I have watched some Liverpool games since the arrival of Klopp, and you can see that the players are enjoying playing for him," he said.
"He is like a father figure and, because you have that trust in him as a player, it makes you totally open to his methods and his ideas which, in the long term, you always see are for the benefit of your game and for the team."
(Reporting by Ian Rodricks in Bengaluru; editing by Amlan Chakraborty)
