JAKE Lever left the track early at Melbourne's training session on Monday after experiencing soreness in his reconstructed left knee.
AFL.com.au understands the issue relates to irritation from scar tissue around where the ligament in Lever's knee was reconstructed.
The star defender's ACL remains intact, with the club's medical staff to monitor his training load over the next week.
It is hoped he will be back out on the track for the club's next main session on Friday, although that could change depending on how he pulls up from Monday's session.
It is not uncommon for players after knee surgery to experience discomfort, especially when they look to increase the intensity of their training.
Lever, who was busily flexing his knee on the track, spoke to the club's doctors for several moments before the decision was made for him to leave the track and not continue his running program.
Meanwhile, midfielder Clayton Oliver has stepped up his running after surgery on both shoulders as the club's draftees reported for duty at Gosch's Paddock on Monday morning.
Oliver had latarjet surgery on both of his shoulders in the off-season and won't be ready to resume contact training until after Christmas.
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The All Australian midfielder started running a fortnight ago after the operations and did not appear to be overly hampered when he pounded the track on Monday.
The midfielder joined Billy Stretch, on the comeback trail from a stress fracture in his toe, Christian Petracca (knee surgery), Neville Jetta (shoulder surgery) and James Harmes (shoulder surgery) in rehab.
Oscar McDonald was also part of the rehab group, while Tim Smith and Jake Lever ran laps with Oskar Baker, who is recovering from a hamstring strain he sustained at the end of the season.
The draftees – Tom Sparrow (pick 27), James Jordon (33), Aaron Nietschke (53), Marty Hore (56), Toby Bedford (75) and rookie Kade Chandler – got some words of advice from Simon Goodwin, who is back at the club after his study tour in the United Kingdom, before being introduced into the drills.
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The players completed repeat 200m sprints at the start of training with Joel Smith, who appeared in top nick, leading the way with Alex Neal-Bullen.
Category B rookies Austin Bradtke and Guy Walker were also both on the track and did not look out of place as they get accustomed to AFL life.
The full squad is officially due back next Monday, although senior players Nathan Jones and Max Gawn have been back in training for several weeks.