Mumm just finished serving a two-match suspension and will join Kane Douglas in the second row.
Dave Dennis, who played lock last week, moves to blindside flanker in the revamped pack.
Ben Mowen drops to the bench.
The Waratahs have decided to keep Berrick Barnes at centre, with Daniel Halangahu keeping his place at flyhalf, while hooker Tatafu Polota-Nau has been cleared to play after an injury scare.
“It was always going to be a bit of a juggling act to see how Dean would come back into the team,” Waratahs coach Chris Hickey. “It was one of those dilemmas that coaches like to have when a number of players are performing well in their position, and it only adds to the questions when there’s players such as Dave [Dennis] and Mummy who can fill more than one role.
“We know Ben will really give us some good punch at the end like he did in the Queensland game, and certainly everyone on the bench has an important role to play for us on Saturday.”
Despite back-to-back losses, Hickey was reluctant to play around with the line-up too much after last week’s match in Pretoria.
“We’ve learned some valuable lessons from the loss to the Bulls and we certainly have a number of things to work on, however we couldn’t really fault the commitment of anyone in the team last week,” said Hickey. “Combinations are coming together, and the confidence in different combinations when the bench players come on is really encouraging and that makes for a strong squad from 1 to 22.
“We’re confident of turning in a strong performance this weekend for our first home game and hopefully we’ll have a big home crowd to welcome us back to Sydney.”
WARATAHS: Sosene Anesi; Lachie Turner, Tom Carter, Berrick Barnes, Drew Mitchell; Daniel Halangahu, Luke Burgess; Wycliff Palu, Phil Waugh (c), Dave Dennis, Kane Douglas, Dean Mumm, Al Baxter, Tatafu Polota-Nau, Benn Robinson.
Reserves: Damien Fitzpatrick, Sekope Kepu, Will Caldwell, Ben Mowen, Josh Holmes, Kurtley Beale, Rob Horne.