With just four Sydney games remaining and last year's unbeaten record at home already in tatters after losses to the Force and Stormers, the defending champions are determined to resurrect "fortress NSW" and keep their finals tilt on track at ANZ Stadium on Saturday.

Open side breakaway Michael Hooper said a win against the Rebels, who grow in confidence and street smarts with every round, was crucial to the team's momentum heading into the back end of the season.

"It would be nice for us to start locking down [home games], we haven't got that many, we've got a South African trip coming, so these games are important to start getting a roll on," Hooper said.

"We beat a New Zealand team [the Hurricanes] last week, we want to beat an Australian team and start moving on like that, so no matter what team we're facing we're putting out our best performance and that's going to carry us through to finals time."

The Rebels arrived in Sydney on Friday as a major potential fly in the ointment for NSW.

Ranked 11th on the ladder but third behind the Waratahs in the Australian conference, a win on Saturday could enable them to draw level with their NSW rivals at the very least. A four-try bonus point win would enable them to overtake the defending champions a day after conference leaders the Brumbies host a depleted Highlanders in Canberra.

After a difficult first four seasons in Super Rugby, the Rebels' early season form - punctuated by upsets over the Crusaders and Brumbies - have conference rivals on notice.

"I don't think they're dark horses, I think they're genuine [finals] contenders," Waratahs coach Michael Cheika said.

"They've only lost one game more than us, they've been playing good football, they've snookered two victories away from home against tough opposition.

"In between the teams I feel there's a real strong respect because of the physicality our games are played at. We like to aim up on that day and Melbourne aim up every time, physically."

The Waratahs have beaten every Australian team once apart from the Force, who ambushed them in round one.

This will be the team's first trip out to ANZ Stadium, and they take a new look pack with Dave Dennis at No.8 and Mitchell Chapman starting in the second row.

"I think Denno's playing really good footy and this will be a pretty seamless change, he's played a lot in the back row," Hooper said.

"With [Test No.8 Wycliff Palu] dropping to the bench it's about player management and I'm sure Cheik has had a plan from a long way out to organise people and load amounts.

"Cliff had a huge impact last week and he'll be looking to have a big impact on the back end of the game this week."