Chelsea manager Antonio Conte has stressed the importance of taking their time over Kurt Zouma's recovery from injury.
The 21-year-old damaged his anterior cruciate ligament when landing awkwardly during a Premier League clash with Manchester United in February and was forced to undergo an operation which ruled him out for the rest of the season.
Zouma is also expected to miss the start of the 2016-17 campaign, and Conte knows from personal experience that they cannot take any shortcuts in his route back to fitness.
"Today he started the aerobic work for the first time. We wait because we must respect the right time for him," he told reporters.
"We know he is recovering but I know he needs more time to recover. It's important we don't push him. I had the same injury and I know from experience when the player is ready to go."
Chelsea begin the new season at home to West Ham United on Monday, August 15.
