Rebels lose Test prop Smith for 12 weeks

The Melbourne Rebels have been rocked with the loss of Test prop Toby Smith for 12 weeks after he underwent hamstring surgery.

The Melbourne Rebels have been rocked with the loss of Test prop Toby Smith for 12 weeks. (AAP)

The Melbourne Rebels' hopes for a fast start to their Super Rugby campaign have been rocked with Test prop Toby Smith undergoing surgery on his hamstring.

The cornerstone of the Rebels pack, Smith, who has four Wallabies caps, is expected to be sidelined for 12 weeks after suffering the injury at training on Tuesday.

Melbourne open their season against the Auckland Blues at AAMI Park next Thursday night, with the loss of Smith compounded by gun flanker Sean McMahon being sidelined for the first six weeks following ankle surgery.

Rebels coach Tony McGahan said he wasn't yet sure of whether he would bring someone else into the squad after only receiving the news on Thursday morning.

"Toby's an international player and he's been here for the last three seasons so he's an important part of what we do certainly from a set piece perspective," McGahan said.

"We've got some really good young guys there so we will just reassess and get on with it."