The Belgium international became the Reds' most expensive stopper of all time when he signed for around £9m in the summer, and Sturridge thinks that his teammate has adapted well to life at the club.
"Simon is a top-class goalkeeper at the start of the season everyone saw what he was all about with that penalty save against Stoke City," Sturridge told the club's official website.
"He set himself a standard. It's difficult as a keeper to be unbelievable in every game.
"But Simon is an unbelievable guy on and off the field and we're so happy to have him here."
The Reds are currently second in the Premier League.