Sturridge has been a vital player for the Reds during the periods when he has managed to avoid the injury problems which have plagued his career over the last few years.
Since joining the club from Chelsea in January 2013, the 26-year-old has scored 47 goals in just 81 matches across nearly three-and-a-half seasons at Anfield.
During the 2013-14 season, when Sturridge netted 24 goals in 33 games in all competitions and struck up a lethal partnership with Luis Suarez, the striker was billed by many as one of the top forwards in England.
Since then, however, injuries have limited the England man to just 19 appearances in the Premier League across nearly two full seasons as he has struggled to recapture the fitness and form of two years ago.
However, Rush still has no doubts about the striker's ability, and claimed to the Metro that Sturridge is one of the greatest players in world football on his day.
Liverpool's record goalscorer said: "Sturridge is one of the best players in the world. If you look when Sturridge plays and the goals he scores, he’s been fantastic.
"But you’ve just got to keep him fit. He’s got the Euros coming up so he’s got a chance between now and the end of the season to prove himself again."
This season, Sturridge has managed just 14 appearances in all competitions due to lengthy injury absences, but he has still managed to find the net seven times.
The former Chelsea and Manchester City man is in line for his first appearance for England in 18 months when Roy Hodgson's side take on the Netherlands at Wembley on Tuesday evening.