The Uruguayan striker, who joined Barcelona earlier this summer, scored 31 goals last term as the Reds came close to winning their first league title in 24 years.
However, Le Saux believes that the Merseysiders will find it difficult to adjust to his absence during the upcoming campaign.
"I just worry for them a bit. Not the goals, but he was such a competitor and demanded so much of everyone around him," he is quoted as saying by BBC Sport.
"You could see he had a desperation to win and I just wonder how much the team will miss that enthusiasm."
Liverpool play their first game of the new season on Sunday when they welcome Southampton to Anfield.