Melbourne face a testing two-game trip to South Africa without their best player after star halfback Will Genia injured his hamstring in the Rebels' loss to the Jaguares.
The Wallabies No.9 has been in vintage form and set up two tries for the Rebels as they surrendered a 13-point lead to fall 25-22 at AAMI Park on Saturday afternoon.
Genia grabbed at his hamstring and immediately left the field after his second break set up a try for fullback Dane Haylett-Petty in the 49th minute.
In a massive blow for the Rebels' hopes in South Africa, scans confirmed a grade one hamstring tear which will keep the veteran from travelling.
He will go for scans on Sunday butsays it doesn't look good.
"We'll assess after his scan whether he will miss a game or even two games," Rebels coach Dave Wessels said on Saturday.
Melbourne will look to include Harrison Goddard in their squad as they face the Bulls in Pretoria and the Stormers in Cape Town.
Goddard was recently named in Australia's side for the World Rugby U20s Championship in Georgia in June but Wessels said he was likely to be available.
"He's got Super Rugby experience and has trained really well but we want him to play for Australia," Wessels said.
"It's a bit of a balancing act and we want to do the right thing by Australian rugby but our understanding is that if Will is ruled out then we will take Harrison."
Wallabies utility back Reece Hodge missed the Jaguares match but is a certainty for the trip, where the Rebels will look for their first win on South African soil.