Melbourne Rebels fullback Mark Gerrard has been ruled out for four weeks with a shoulder injury. Gerrard hurt his shoulder in a tackle in the narrow 34-32 loss to the Sharks on Friday and had a scan on Saturday. Melbourne coach Rod Macqueen said the injury was an untimely one for the Rebels as the former Wallaby had been in good form. "It's really disappointing to be losing Mark because he's been a great contributor to the team, particularly over the last couple of games," he said. "Unfortunately there's nothing we can do about the injury situation and we'll just have to assess the ramifications over the next couple of days."