Melbourne Rebels lock Kevin O'Neill has been ruled out of Saturday's Super Rugby clash against the Western Force after aggravating a calf injury.

The combination of O'Neill's 201cm, 104kg frame and an economy class flight from Melbourne to Perth wasn't a good match for the 29-year-old New Zealander.

His place has been taken on the run-on side by Hugh Pyle with Adam Byrnes coming on to the bench for the crunch match.

Veteran prop Greg Somerville said 22-year-old Pyle had made the most of his opportunities this season, and predicted he would again have an impact.

"He's come in and played well," Somerville said.

"He's pretty athletic and brings that running game around the field."

Melbourne are looking for their first away win of the competition in a match that is the first of a budding rivalry against fellow "new boys" the Force.

The Rebels are preparing to face a desperate home side after Force coach Richard Graham applied the blow-torch and claimed his side had to win to keep alive any finals hopes.

The Perth side have only managed one victory and a draw in five matches.

"They're probably in the same position of us, a win is important to us going into the bye," Somerville said.

"They've come back from Africa and want to bounce back in front of their home fans and we want to try and show we can be consistent."

The Force were thrashed 51-16 by the Stormers last round, after a build-up hampered by illness to a several players.

Skipper Nathan Sharpe said the loss had "hurt".

"We need to make sure our game is good, last weekend we made too many mistakes, that's a lesson for us," Sharpe said.

"The Rebels had a good win against the Hurricanes and they're going to be excited about coming over here.

"I think they see us as an opportunity, which is good for us, we enjoy that."

Somerville said rivalry between the two sides was natural, both being Australian and the newest franchises in the competition.

"It's going to be, who's going to be the best new boys on the block.

"The matches over the next few years will determine that.

"It's too early to call just yet."

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