Sunderland boss Steve Bruce insists he won't rush any of the club's long-term casualties back into action too soon.
"It's a little bit too soon (for a first-team return) at the moment,'' Bruce told the club's website. "We're delighted to see Fraizer, Michael and Lee in and around the training ground.
"If you look at pre-season, we have six weeks off and then six weeks of intensive training plus six or seven friendly games.
"That tells you when someone has been out for six weeks, two months, it's difficult to come back straight away. We can't rush them back, which would be easy to do. They've been out for a long time.''
On-loan striker Danny Welbeck is also sidelined and continues to receive treatment.
Midfielder Jack Colback picked up a slight muscle strain in training earlier this week but Bruce expects the midfielder to be available for Saturday's Barclays Premier League clash with Everton at Goodison Park.