But they quickly made up their minds when Trent Alexander-Arnold produced a superb free-kick to put the hosts ahead after just seven minutes.
Rangers keeper Allan McGregor, 40, made some fine saves, including four to deny Darwin Nunez his first goal for Liverpool to keep his side on the hunt at half-time.
However, seven minutes into the second half, Leon King’s tackle caught the legs of Luis Díaz, who conceded a penalty.
Mohamed Salah came forward and found the ball in the middle when McGregor was unable to repeat the heroism he showed against Napoli.
“It was exactly what we needed. It was a great solid performance,” said Klopp, who changed from his usual 4-3-3 formation to a 4-2-3-1.
“Sometimes you have to change things.”