Wallabies and Rebels star James O'Connor is in doubt to play against current Super Rugby champions the Reds even though he has recovered from his liver damage.

O'Connor has been given the green light to resume contact training following scans on his lacerated liver but he is now struggling with a hamstring injury.

O'Connor originally suffered liver damage whilst playing for the Rebels against the Waratahs last month.

The Wallaby back and his coach are still hoping that he can return for the Rebels home match against the Reds on June the 29th at AAMI Park as it will be Rebels captain Stirling Mortlock's Australian farewell.

"He's still a good chance for us for the Reds which is pleasing," Rebels coach Damien Hill told AAP.

"He got clearance from the scans but the hamstring's still not 100 per cent.

"James is one of those naturally fit players so his fitness shouldn't be a problem."

The Rebels are also sweating on utility back Mark Gerrard who also has a hamstring injury.